Due to rapid urbanization and industrialization, the consumption of electricity in the world is expected to increase, thus leads to the fast development of the renewable energy industry. In 2016, 24.5 of the electricity is produced by renewable energy. There are several types of renewable energy, e.g. solar, wind, and ocean wave. The ocean wave energy is identified to have the greatest potential for electricity generation. There are various types of wave energy converter (WEC) that have been designed for harnessing the wave energy, e.g. the oscillating water column, salter duck, point absorber, water dagon etc. Due to the smaller dimension, the point absorber is the most suitable WEC to be deployed in an array configuration, whereby each isolated WEC interacts and alters the vicinity of the wave formation by absorbing, radiating, and diffracting the wave. Subsequently, the wave interference will also affect the WEC's performance. The objective of the present study is to investigate the optimum separation distance, d, that would resulting to an optimum performance between two WECs in an array configuration using a computational fluid dynamics (CFD) software. The analysis considered an isolated WEC and two WECs, i.e. the heaving point absorbers with three point catenary mooring lines. The influence of the separation distance towards diffraction and response amplitude operator (RAO) of an array of two WECs was evaluated. The optimum production of the wave energy by the heaving point absorber is observed to be highly dependant on the relative heave motion of the two WECs 1. In the present study, it shows that the optimum distance between two WECs in an array configuration is 20 m, whereby the maximum heave RAO were identified. © The Authors, published by EDP Sciences, 2018.