Knowledge of sensor node 3D location in a sensor network is more important, because many practical applications needs to know the location of sensor data source. This paper presents a new technique for finding indoor 3D location of a sensor node by using Received Signal Strength Indication (RSSI). Proposed localization algorithm is derived from centroid algorithm with composition of empirical path loss model. It gives less error in estimating 3D location of sensor node in a sensor network when compared to its actual location. Algorithm has been implemented and analysed by using IITH motes and a Mobile Robot. © 2014 National Institute of Information and Communicatio.