Oscillating foil energy harvesting devices are increasingly being considered as a sustainable energy alternative, especially in rivers and tidal areas. This paper applies CFD to an oscillating foil power generation device in order to explore the effects of pitching amplitude, the ratio of heaving amplitude to chord length, and the reduced frequency to the energy harvesting efficiency. Ansys Fluent 17.2 was used for this study, and the results are compared to experimental results that have been previously documented in the open literature. Configurations examined included pitching amplitudes of 65, 70, 75, and 80 degrees; heaving ratios of 0.4, 0.6, and 0.8; and reduced frequencies of 0.1, 0.12, 0.14, and 0.16. Results seems to indicate that the optimal reduced frequency is related to the heaving ratio, with the pitching amplitude only creating slight variations in the power produced by the foil. In the data, configurations with a heaving ratio of 0.4 have highest efficiency at reduced frequencies of either 0.14 or 0.16, but efficiency remains high at both points, which indicates the possibility of a peak in between the two points. Configurations with heaving ratio of 0.6 peak at reduced frequency 0.14 with a significant drop off at reduced frequency of 0.16. Finally, configurations with a heaving ratio of 0.8 show a peak at 0.12 reduced frequency and a significant drop at 0.14 and 0.16. These results suggest that OFEH devices can be effectively optimized for different and potentially varying operating conditions that may be encountered during practical implementation of OFEH technology.