This study experimentally investigated natural convection in an oscillating cylindrical enclosure to simulate heat transfer inside a buoy of a wave power generator. Mechanical oscillations were applied vertically to simulate the operating conditions of a wave power generator extracting energy from the surface motion of ocean waves. The Rayleigh numbers used in this study ranged from 50,000 to 600,000. Enclosures of various heights H (2.5, 3, 4, and 5 cm) and oscillations of various frequencies (1 and 2 Hz) were investigated. In addition, pin fins of length L were attached to the heat transfer area, and the heat transfer coefficient variation was examined at various L/H ratios (0.4, 0.33, 0.25, and 0.2). The results indicate that the pin fins enhanced the heat transfer under both stationary and oscillating conditions by up to 30%. The mechanical oscillation did not cause considerable changes in heat transfer based on the tested parameters, and the maximal heat transfer variation was less than 10%. (C) 2015 Elsevier Ltd. All rights reserved.