A 2D mathematical modeling was developed to analyze the mass transport in a proton exchange membrane fuel cell. The pin fins were inserted in the flow channel to improve reactant gas distribution in the gas diffusion layer (GDL). The effect of rectangular and triangular shape of fins and different title angles of 4, 6 and 8 degrees on the reactant gas transport were examined. The results showed that performance of rectangular fins are better than triangular fins due to increasing reactant spread over the GDL. The effect of three independent factors including length and width of blocks and hydrogen gas velocity on the response (hydrogen gas diffusion to GDL and pressure drop in anode channel) was investigated using analysis of variance (ANOVA). The results showed that block height and hydrogen gas velocity are the most important factors affecting the responses. Also, response surface methodology (RSM) method was used to predict the optimal conditions to achieve the minimum the pressure drop and maximum the total flux magnetic H-2 to GDL in anode channel. The result of the optimization process shows that a gas velocity of 4.22 m/s and the block with height and width of 3 mm are the optimal conditions. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.