[en] An analytical model based on homotopy perturbation method is developed to analyze the thermal performance and optimum geometric dimensions of a T-shaped fin under fully wet condition by adopting a linear model between the humidity ratio of saturated air adjacent to the fin surface and the corresponding fin surface temperature. The optimization analysis is done by using the Lagrange multiplier technique and by maximizing the heat transfer rate for a constraint fin volume. The analysis is done in a comparative way between linear variation and cubic variation of the humidity ratio with the corresponding saturation temperature. Finally, it can be concluded that the consideration of the linear model for analysis of wet T-shaped fin does not introduce any significant deviation in results