Wireless Sensor Network (WSN) is composed of low cost small sensors nodes that are spatially distributed and are linked through a wireless network which gathers data and transmits to the sink node. WSN enables the monitoring of different environmental conditions for both military and civil purposes. WSN is application specific as it is a subset of ad-hoc networks. WSNs are generally assumed to be energy restrained clustering algorithms are used to conquer the problem of energy efficiency. In this paper, the authors propose an improved O-LEACH (Low Energy Adaptive Clustering Hierarchy) technique which selects the cluster head according to natural selection technique.