Many mechanisms to improve the performance have been proposed in the IEEE 802.15.4 Wireless sensor networks area, due to its high influence in the modern day world. Most of them have improved the performance of the network compared to the standard CSMA/CA backoff method. But still there are improvements to almost every method proposed. In this paper, we have proposed a hybrid binary exponential backoff (HBEB), where we have used two mechanisms to effectively increase the performance, when there are moderate numbers of nodes. The performance analysis using markov chain analysis has been given in this paper along with simulation results for the proposed method.