This paper presents a novel impulse turbine configuration for use in OWC systems which was developed as part of a UK Department of Trade and Industry part-funded research programme carried out by Dresser-Rand Company Ltd and Cranfield University. The turbine demonstrates increased levels of efficiency in comparison with existing impulse designs across a wide range of incident flows. This is achieved by a design which does not contain any moving parts besides the rotor, meaning that good reliability and economic cost of production should be achievable. The results presented are based on a validated and calibrated numerical approach and describes that a total-static efficiency of about 75% for a full scale turbine has been achieved. The numerical results have been validated against the data obtained at unique test facility located at Cranfield University which is capable of simulating the aerodynamic conditions that turbines are exposed to in OWC power plants. Moreover, a unique numerical study of the effects of inlet flow distortion on the performance of the impulse turbine for use in OWC power plants is also presented.