Mobile Technology is growing rapidly. Usages of smart phones are increased for critical financial applications. This leads to many security issues as well. Implementing security features into such critical financial applications can minimize the transaction risk .Traditionally RSA, DH public key cryptography algorithms has been used. However ECC has proven results for smaller key size requirement which is more useful for resource constrained devices that take less memory, less bandwidth and less power consumption. In our paper, we have proved ECC's strength with respect to RSA. This paper contributes on implementation of ECC over GF (2m) for smart phone OS which is used in mobile devices. Our experiment shows that ECC takes less computation time efforts than RSA when key size becomes greater than 512 bits which is advantageous on mobile or smart phones. In our implementation memory consumption is reduced as we are computing elliptic curve points dynamically when we need it and cipher text size is also reduced. We are avoiding cryptanalytic attack by eliminating same cipher text pattern generation. An experiment study is conducted on android OS which is one of the popular smart phone OS to show the effectiveness of proposed algorithm and also addressed cryptanalytic attack. © 2011 Springer-Verlag.