accepted As you're making a HTTP GET request, data needs to be key-value pairs, as that's how a GET request is constructed (e.g. /get.php?var1=a&var2=b&var3=c ). jQuery.ajax() accepts this key-value pairs as either an object map, or a string, as described in the documentation: Data to be sent to the server. It is converted to a query string, if not already a string. It's appended to the url for GET-requests. See processData option to prevent this automatic processing. Object must be Key/Value pairs. If value is an Array, jQuery serializes multiple values with same key based on the value of the traditional setting (described below). So you should use either; data : "value=22" or data : { value : 22 } Then in PHP you can use $_GET['value'] to retrieve it.