The evolution of modern mobile devices towards novel Radio Frequency (RF) capabilities, such as Near Field Communication (NFC), leads to a potential for delivering innovative mobile services which is still partially unexplored. Mobile NFC micro-payments systems can enhance the daily shopping experience, but the access to payment security resources of a mobile device (e.g. the “Secure Element”) by third party applications is still blocked by smartphone and OS manufacturers. In this paper, the IDA-Pay system is presented, an innovative and secure NFC micro-payment system based on peer-to-peer NFC operating mode for Android mobile phones. It allows to guarantee mobile-to-POS micro-payment services, bypassing the need for special hardware. A validation scenario is also depicted in order to demonstrate the system effectiveness.