Temporal Key Integrity Protocol (TKIP) is the IEEE TaskGroupi solution for the security loop holes present in the already widely deployed 802.11 hardware. It is a set of algorithms that wrap WEP to give the best possible solution given design constraints such as paucity of the CPU cycles, hardwiring of the WEP encryption algorithm and software upgrade dependent. Thus, TKIP is significantly more difficult and challenging to implement and optimise than WEP. The objective of this research is to examine the cost and benefit of TKIP security mechanisms and optimise its implementation to reduce security overhead for better performance. We propose a modified TKIP (MoTKIP) with improved packet encapsulation and decapsulation procedure that reduces computation and packet overhead in classic TKIP substantially and optimises total wireless network throughput rates.