This paper deals with numerical studies of wave interaction with an Oscillating Wave Surge Converters (OWSC) using a Godunov–type SPH method. The use of a Riemann solver in calculating the density field results in a smoother SPH pressure field. Hence, a more accurate estimation of loads on the OWSC is achieved. Furthermore, the Lagrangian form of the RANS k–ε model is included in the SPH equations to better capture the turbulent features of the flow. SPH simulations were performed in both two–dimensions (2D) and three–dimensions (3D) and results for the flow pattern and loads are compared with experimental data.