In wireless sensor networks (WSNs) the position information of individual nodes is a matter of vital importance because allows the implementation of necessary network functions such as routing, querying and other applications. The objective of this paper is to propose an algorithm of three-dimensional distributed range-free localization for WSNs, using a mobile beacon (MB) equipped with a rotary and tilting directional antenna. This algorithm, denominated as the three-dimensional azimuthally defined area localization algorithm (3D- ADAL), is executed in each sensor node and is based only on the analysis of the information received from the MB, therefore is energy efficient and contributes to extend the lifetime of the sensor network. Additionally the proposed algorithm has the advantage of being simple and economical. The simulation results show that the proposed algorithm is a practical, effective and accurate method for a three-dimensional location of sensor nodes in a WSN. In wireless sensor networks (WSNs) the position information of individual nodes is a matter of vital importance because allows the implementation of necessary network functions such as routing, querying and other applications. The objective of this paper is to propose an algorithm of three-dimensional This algorithm, denominated as the three-dimensional azimuthally defined area localization algorithm (3D-ADAL), is executed in each sensor node and the based on the analysis of the information received from the MB, therefore is energy efficient and contributes to extend the lifetime of the sensor network. algorithm is a practical, effective and accurate method for a three-dimensional location of sensor nodes in a WSN.