The proton exchange membrane fuel cell (PEMFC) performance depends on the design parameters like landing-to-channel width ratio (L:C), channel depth, shape and number of passes on the flow channel, and operating parameters like temperature, pressure, the stoichiometric ratio of reactants, relative humidity, back pressure on the anode, and cathode flow channels. In this paper, optimization of design and operating parameters such as various landing -to-channel width ratios (L:C -1:1, 1:2, 2:1, and 2:2) of the interdigitated flow channel, pressure, temperature, and the anode and cathode inlet reactant masses on the 25cm^2 electrode surface active area of the PEMFC was carried out. A three dimensional (3-D) PEMFC model was created by Creo Parametric 1.0, meshed by ICEM 14.0 and simulated... using the CFD Fluent 14.0 software packages. The optimization of the design and operating parameters was carried out in two stages using Minitab 17 with a standard orthogonal array of the Taguchi method. From the first stage of analysis, it was inferred that the landing-to-channel width ratio (L:C - 1:1) has the biggest influence on the PEMFC performance and the square of response factor (R^2) was achieved by the Taguchi method at 97.95%. In the second stage of analysis, fine-tuned optimization was performed on selected factors which cause an increase in power density of 0.81. Also, R^2 was achieved at 100 % and the results were also validated using the CFD Fluent 14.0 software packages.