In this study, a practical card-emulated relay attack is implemented on Near Field Communication (NFC) equipped mobile devices. NFC is a promising communication technology which is also used in smart mobile devices. As an effective and flexible communication technology, NFC is frequently used in innovative solutions nowadays such as payments, access control etc. Because of the nature of these transactions, security is a critical issue that should be considered in system design and development phases. Although inherited from Radio Frequency Identification (RFID) technology, NFC security needs, requirements and solutions differ in terms of its usage areas and solutions. Based on these parameters, security precautions in communication layer of RFID technology do not prevent relay attacks occurred in the application layer NFC solutions. This study is conducted to prove relay attack practicability with using only mobile phones for relaying credentials instead of RFID based smart cards in an access control application. The Host Card Emulation (HCE) mode also eases relay attacks in NFC communication. The study explains the conceptual description of proposed relay attack, development and operating logic of mobile applications working based on card emulation mode and server software and also data communication basics between modules and web services descriptions.