In this manuscript the function projective synchronization between different fractional order chaotic systems with uncertain parameters using modified adaptive control method is studied. The adaptive function projective synchronization controller and identification parameter laws are developed on the basis of Lyapunov stability theory. The method is successfully applied for the function projective synchronization between some fractional order chaotic systems. The analysis of the synchronization time with variations of fractional order derivatives is the key feature of the present manuscript. The numerical simulation results clearly show that the modified method is very much efficient and reliable for synchronizing the two different fractional order chaotic systems. (C) 2014 Elsevier Ltd. All rights reserved.