The objective of this paper is to report the effects of Reynolds number and hub-to-tip ratio on the performance of the impulse turbine for wave energy conversion. The turbine was investigated experimentally under steady and sinusoidally oscillating flow conditions by model testing. As a result, it was found that the critical value of Reynolds number and the optimum hub-to-tip ratio are approximately 4.0× 104 and 0.7, respectively. Furthermore, their effect on starting characteristics have been clarified. © 2004 by ASME.