diff --git a/app/src/main/java/org/sensingkit/crowdsensing_android/CrowdSensing.java b/app/src/main/java/org/sensingkit/crowdsensing_android/CrowdSensing.java
index 5008691..88cbb6f 100644
--- a/app/src/main/java/org/sensingkit/crowdsensing_android/CrowdSensing.java
+++ b/app/src/main/java/org/sensingkit/crowdsensing_android/CrowdSensing.java
@@ -21,13 +21,17 @@
 
 package org.sensingkit.crowdsensing_android;
 
+import android.Manifest;
+import android.app.Activity;
 import android.app.ActivityManager;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
 import android.content.ServiceConnection;
+import android.content.pm.PackageManager;
 import android.os.Bundle;
 import android.os.IBinder;
+import android.support.v4.app.ActivityCompat;
 import android.support.v7.app.ActionBarActivity;
 
 import android.util.Log;
@@ -59,9 +63,30 @@ private enum SensingStatus {
     // Services
     SensingService mSensingService;
     boolean mBound = false;
+    private static final int REQUEST_EXTERNAL_STORAGE = 1;
+    private static String[] PERMISSIONS_STORAGE = {
+            Manifest.permission.READ_EXTERNAL_STORAGE,
+            Manifest.permission.WRITE_EXTERNAL_STORAGE
+    };
 
+    //persmission method -> check if the permissions are OK
+    public static void verifyStoragePermissions(Activity activity) {
+        // Check if we have read or write permission
+        int writePermission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.WRITE_EXTERNAL_STORAGE);
+        int readPermission = ActivityCompat.checkSelfPermission(activity, Manifest.permission.READ_EXTERNAL_STORAGE);
+
+        if (writePermission != PackageManager.PERMISSION_GRANTED || readPermission != PackageManager.PERMISSION_GRANTED) {
+            // We don't have permission so prompt the user
+            ActivityCompat.requestPermissions(
+                    activity,
+                    PERMISSIONS_STORAGE,
+                    REQUEST_EXTERNAL_STORAGE
+            );
+        }
+    }
     @Override
     protected void onCreate(Bundle savedInstanceState) {
+        verifyStoragePermissions(this); // verify once the permission ( only for Marshmallow)
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_crowd_sensing);