A wireless network consisting of a large number of small sensors with limited battery power can be an effective tool for gathering data in a variety of environments. Clustering sensors into groups, so that sensors communicate information only to cluster-heads and then the cluster-heads communicate the aggregated information to the base station, may save energy. In this paper, we propose an optimal energyadaptive clustering algorithm which is motivated from the LEACH protocol presented in [4]. We optimize LEACH?s random cluster-head selection algorithm to ensure the balanced energy depletion over the whole network thus prolongs the network lifetime. Simulation results show that our algorithm outperforms LEACH by about 20% to 35% when 1%, 50%, 100% of nodes die for different network sizes and topologies.