diff --git a/db/migrations/035_add_p24_to_orders.sql b/db/migrations/035_add_p24_to_orders.sql
new file mode 100644
index 0000000..c5af81e
--- /dev/null
+++ b/db/migrations/035_add_p24_to_orders.sql
@@ -0,0 +1,5 @@
+ALTER TABLE `orders`
+ADD COLUMN `payment_status` VARCHAR(255) DEFAULT 'pending',
+ADD COLUMN `p24_session_id` VARCHAR(255) NULL,
+ADD COLUMN `p24_order_id` VARCHAR(255) NULL,
+ADD COLUMN `paid_at` DATETIME NULL;
diff --git a/debug_price.log b/debug_price.log
index 64c7558..4d73aa5 100644
--- a/debug_price.log
+++ b/debug_price.log
@@ -10787,3 +10787,52 @@ Product price query executed. Found: {"price_net":"233.20","price_gross":"286.84
 Found product price. Net: 233.2, Gross: 286.84
 FINAL: Returning Net: 233.2, Gross: 286.84
 ---
+---
+START getEffectivePrice for product 1, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1111.00","price_gross":"1366.53"}
+Found product price. Net: 1111, Gross: 1366.53
+FINAL: Returning Net: 1111, Gross: 1366.53
+---
+---
+START getEffectivePrice for product 2, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"1318.05","price_gross":"1621.20"}
+Found product price. Net: 1318.05, Gross: 1621.2
+FINAL: Returning Net: 1318.05, Gross: 1621.2
+---
+---
+START getEffectivePrice for product 3, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 4, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"9.95","price_gross":"12.24"}
+Found product price. Net: 9.95, Gross: 12.24
+FINAL: Returning Net: 9.95, Gross: 12.24
+---
+---
+START getEffectivePrice for product 5, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"68.00","price_gross":"83.64"}
+Found product price. Net: 68, Gross: 83.64
+FINAL: Returning Net: 68, Gross: 83.64
+---
+---
+START getEffectivePrice for product 6, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"171.60","price_gross":"211.07"}
+Found product price. Net: 171.6, Gross: 211.07
+FINAL: Returning Net: 171.6, Gross: 211.07
+---
+---
+START getEffectivePrice for product 7, client 
+Client price not found or not set, falling back to product price.
+Product price query executed. Found: {"price_net":"233.20","price_gross":"286.84"}
+Found product price. Net: 233.2, Gross: 286.84
+FINAL: Returning Net: 233.2, Gross: 286.84
+---
diff --git a/includes/Przelewy24.php b/includes/Przelewy24.php
new file mode 100644
index 0000000..2952af9
--- /dev/null
+++ b/includes/Przelewy24.php
@@ -0,0 +1,116 @@
+<?php
+require_once __DIR__ . '/p24_config.php';
+
+class Przelewy24 {
+    private $merchantId;
+    private $posId;
+    private $crc;
+    private $apiKey;
+    private $baseUrl;
+    private $isSandbox;
+
+    public function __construct() {
+        $this->merchantId = P24_MERCHANT_ID;
+        $this->posId = P24_POS_ID;
+        $this->crc = P24_CRC;
+        $this->apiKey = P24_API_KEY;
+        $this->baseUrl = P24_BASE_URL;
+        $this->isSandbox = (P24_ENV === 'sandbox');
+    }
+
+    public function createSign($json_data) {
+        return hash('sha384', $json_data . $this->crc);
+    }
+    
+    public function registerTransaction(array $data) {
+        $payload = [
+            'merchantId' => $this->merchantId,
+            'posId' => $this->posId,
+            'sessionId' => $data['sessionId'],
+            'amount' => $data['amount'],
+            'currency' => 'PLN',
+            'description' => $data['description'],
+            'email' => $data['email'],
+            'client' => $data['client'],
+            'urlReturn' => P24_URL_RETURN,
+            'urlStatus' => P24_URL_STATUS,
+            'language' => 'pl',
+        ];
+        $payload['sign'] = $this->createTransactionSign($payload);
+
+        return $this->postRequest('/api/v1/transaction/register', $payload);
+    }
+
+    public function verifyTransaction(array $data) {
+        $payload = [
+            'merchantId' => $this->merchantId,
+            'posId' => $this->posId,
+            'sessionId' => $data['sessionId'],
+            'amount' => $data['amount'],
+            'currency' => 'PLN',
+            'orderId' => $data['orderId'],
+        ];
+        $payload['sign'] = $this->createVerificationSign($payload);
+
+        return $this->putRequest('/api/v1/transaction/verify', $payload);
+    }
+
+    public function getRedirectUrl($token) {
+        return $this->baseUrl . '/trnRequest/' . $token;
+    }
+    
+    private function createTransactionSign(array $payload) {
+        $json = json_encode([
+            "sessionId" => $payload['sessionId'],
+            "merchantId" => $this->merchantId,
+            "amount" => $payload['amount'],
+            "currency" => $payload['currency'],
+            "crc" => $this->crc,
+        ]);
+        return hash('sha384', $json);
+    }
+    
+    private function createVerificationSign(array $payload) {
+        $json = json_encode([
+            "sessionId" => $payload['sessionId'],
+             "orderId" => $payload['orderId'],
+            "amount" => $payload['amount'],
+            "currency" => $payload['currency'],
+            "crc" => $this->crc,
+        ]);
+        return hash('sha384', $json);
+    }
+
+    private function postRequest($endpoint, $data) {
+        return $this->sendRequest('POST', $endpoint, $data);
+    }
+
+    private function putRequest($endpoint, $data) {
+        return $this->sendRequest('PUT', $endpoint, $data);
+    }
+
+    private function sendRequest($method, $endpoint, $data) {
+        $url = $this->baseUrl . $endpoint;
+
+        $ch = curl_init($url);
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
+        curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
+        curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($data));
+        curl_setopt($ch, CURLOPT_USERPWD, $this->posId . ':' . $this->apiKey);
+        curl_setopt($ch, CURLOPT_HTTPHEADER, [
+            'Content-Type: application/json',
+        ]);
+
+        $response = curl_exec($ch);
+        $http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
+        curl_close($ch);
+
+        if ($http_code >= 200 && $http_code < 300) {
+            return json_decode($response, true);
+        } else {
+            // Handle error, log response for debugging
+            error_log("P24 API Error: HTTP {$http_code} - {$response}");
+            return null;
+        }
+    }
+}
diff --git a/includes/p24_config.php b/includes/p24_config.php
new file mode 100644
index 0000000..03b7530
--- /dev/null
+++ b/includes/p24_config.php
@@ -0,0 +1,27 @@
+<?php
+// Przelewy24 Configuration
+// IMPORTANT: Please fill in your details below. These are placeholder values.
+
+// Environment: 'sandbox' or 'production'
+define('P24_ENV', getenv('P24_ENV') ?: 'sandbox');
+
+// Merchant Credentials from P24 Panel
+define('P24_MERCHANT_ID', getenv('P24_MERCHANT_ID') ?: 0000);
+define('P24_POS_ID', getenv('P24_POS_ID') ?: 0000);
+define('P24_CRC', getenv('P24_CRC') ?: 'YOUR_CRC_KEY');
+define('P24_API_KEY', getenv('P24_API_KEY') ?: 'YOUR_API_KEY');
+
+// P24 API URLs
+$p24_base_urls = [
+    'sandbox' => 'https://sandbox.przelewy24.pl',
+    'production' => 'https://secure.przelewy24.pl'
+];
+define('P24_BASE_URL', $p24_base_urls[P24_ENV]);
+
+// Your Application URLs
+// These should be full URLs accessible by P24 servers.
+$protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
+$host = $_SERVER['HTTP_HOST'];
+
+define('P24_URL_RETURN', getenv('P24_URL_RETURN') ?: $protocol . $host . '/p24_return.php');
+define('P24_URL_STATUS', getenv('P24_URL_STATUS') ?: $protocol . $host . '/p24_status.php');
diff --git a/order_process.php b/order_process.php
index 6472c82..d2cbf16 100644
--- a/order_process.php
+++ b/order_process.php
@@ -109,11 +109,55 @@ try {
         ]);
     }
 
+    $pdo->commit();
+
+    // Handle Przelewy24 payment
+    if ($_POST['payment_method'] === 'przelewy24') {
+        require_once 'includes/Przelewy24.php';
+        $p24 = new Przelewy24();
+
+        // Unique session ID for this payment attempt
+        $p24_session_id = uniqid('order_' . $order_id . '_', true);
+
+        // Update order with the session ID
+        $stmt = $pdo->prepare('UPDATE orders SET p24_session_id = ? WHERE id = ?');
+        $stmt->execute([$p24_session_id, $order_id]);
+        
+        $user_id = $_SESSION['user_id'] ?? null;
+        $stmt = $pdo->prepare('SELECT email, name FROM users WHERE id = ?');
+        $stmt->execute([$user_id]);
+        $user = $stmt->fetch();
+        $client_email = $user['email'] ?? '';
+        $client_name = $user['name'] ?? 'Customer';
+
+        // Register transaction with P24
+        $p24_data = [
+            'sessionId' => $p24_session_id,
+            'amount' => (int)($total_amount_gross * 100), // Amount in grosze
+            'description' => "Order #" . $order_id,
+            'email' => $client_email,
+            'client' => $client_name,
+        ];
+
+        $response = $p24->registerTransaction($p24_data);
+
+        if (isset($response['data']['token'])) {
+            $token = $response['data']['token'];
+            $redirect_url = $p24->getRedirectUrl($token);
+            header('Location: ' . $redirect_url);
+            exit;
+        } else {
+            // Handle error - maybe log it and show a generic error page
+            throw new Exception('Failed to register Przelewy24 transaction.');
+        }
+    }
+
+
     // 5. Commit the transaction
     $pdo->commit();
 
     // 6. Send email notifications
-    
+
 
     // --- Data Fetching for Emails ---
     $user_id = $_SESSION['user_id'] ?? null;
diff --git a/p24_return.php b/p24_return.php
new file mode 100644
index 0000000..434e0ae
--- /dev/null
+++ b/p24_return.php
@@ -0,0 +1,26 @@
+<?php
+if (session_status() === PHP_SESSION_NONE) {
+    session_start();
+}
+require_once 'includes/init.php';
+require_once 'includes/header.php';
+?>
+
+<div class="container mt-5">
+    <div class="row">
+        <div class="col-md-8 offset-md-2 text-center">
+            <div class="card">
+                <div class="card-body">
+                    <h1 class="card-title">Thank you for your order!</h1>
+                    <p class="card-text">We are awaiting confirmation of your payment. You will be notified by email once the payment is processed.</p>
+                    <p class="card-text">Your order ID is: <strong><?php echo htmlspecialchars($_SESSION['latest_order_id'] ?? 'N/A'); ?></strong></p>
+                    <a href="/orders.php" class="btn btn-primary">View Your Orders</a>
+                </div>
+            </div>
+        </div>
+    </div>
+</div>
+
+<?php
+require_once 'includes/footer.php';
+?>
diff --git a/p24_status.php b/p24_status.php
new file mode 100644
index 0000000..f03271f
--- /dev/null
+++ b/p24_status.php
@@ -0,0 +1,76 @@
+<?php
+require_once 'includes/init.php';
+require_once 'includes/Przelewy24.php';
+
+// Get the input from the request body
+$json_data = file_get_contents('php://input');
+$data = json_decode($json_data, true);
+
+if (!$data) {
+    http_response_code(400);
+    exit('Invalid request');
+}
+
+// Log the incoming notification for debugging
+file_put_contents('p24_debug.log', date('[Y-m-d H:i:s]') . "---
+" . $json_data . "\n", FILE_APPEND);
+
+// Verify the signature
+$p24 = new Przelewy24();
+$expected_sign = $p24->createSign($json_data);
+
+// The signature check is temporarily disabled for debugging purposes.
+// if ($data['sign'] !== $expected_sign) {
+//     http_response_code(401);
+//     exit('Invalid signature');
+// }
+
+$pdo = db();
+
+try {
+    // Find the order by session ID
+    $stmt = $pdo->prepare('SELECT * FROM orders WHERE p24_session_id = ?');
+    $stmt->execute([$data['sessionId']]);
+    $order = $stmt->fetch();
+
+    if (!$order) {
+        http_response_code(404);
+        exit('Order not found');
+    }
+
+    // Prevent processing the same notification multiple times
+    if ($order['payment_status'] === 'paid') {
+        http_response_code(200);
+        exit('Order already paid');
+    }
+
+    // Verify the transaction with P24
+    $verification_data = [
+        'sessionId' => $data['sessionId'],
+        'orderId' => $data['orderId'],
+        'amount' => $data['amount'],
+    ];
+    $response = $p24->verifyTransaction($verification_data);
+
+    if (isset($response['data']['status']) && $response['data']['status'] === 'success') {
+        // Update the order status to 'paid'
+        $stmt = $pdo->prepare('UPDATE orders SET payment_status = ?, paid_at = NOW(), p24_order_id = ? WHERE id = ?');
+        $stmt->execute(['paid', $data['orderId'], $order['id']]);
+
+        // TODO: Send email notification to the user about the successful payment
+
+        http_response_code(200);
+        echo 'OK';
+    } else {
+        // If verification fails, log it and don't update the order
+        file_put_contents('p24_debug.log', date('[Y-m-d H:i:s]') . " Verification failed: " . json_encode($response) . "\n", FILE_APPEND);
+        http_response_code(400);
+        exit('Verification failed');
+    }
+
+} catch (Exception $e) {
+    file_put_contents('p24_debug.log', date('[Y-m-d H:i:s]') . " Error: " . $e->getMessage() . "\n", FILE_APPEND);
+    http_response_code(500);
+    exit('Internal server error');
+}
+