Fuel cell is a system that converts chemical energy to electrical energy from an oxidation-reduction reaction of hydrogen and oxygen. In this study, Pt/C catalyst, solvent, and a binder agent were mixed to prepare catalyst ink. First, we applied carbon black ink to the carbon paper to supply hydrophobic and hydrophilic structure on its surface, which is called as microporous layer (MPL). Then catalyst ink was deposited on the treated carbon paper to form gas diffusion layers (GDLs) for anode and cathode side of the fuel cell. At this position, catalyst layer surfaces and carbon paper were analyzed by using scanning electron microscopy (SEM) and it was seen by energy dispersive spectroscopy (EDS) analysis that the catalysts were spread uniformly on a carbon paper. A membrane is fixed between GDLs and hot-pressed at 120 degrees C, 75 kg cm (-2) to compose membrane electrode assembly (MEA). In a fuel cell test unit, MEA has internal resistance, which was evaluated by applying current interrupt method and current-voltage curve was drawn by load application. As a result of the test, I-V curves were formed and compared with characteristic curve of commercial MEA. It was seen that the shapes of the curves are similar. Maximum power values are 100, 275, and 390 mW for homemade MEA without MPL, with MPL, and commercial MEA, respectively. MEA without MPL was susceptible to flooding, especially at high-currrent values. MPL is helpful to increase the porosity of the diffusion layer and this effect can improve the oxygen transfer rate and lead to a higher performance. Compared with commercial MEA, homemade MEA did not reach high-current and -power values due to lots of parameters which affects the fuel cell performance as catalyst activity, conditions of MEA preparation, and disorder of measurement conditions, etc. Copyright (C) 2010 John Wiley & Sons, Ltd.