The aim of this thesis is to investigate the effect of preparation conditions of Membrane Electrode Assembly (MEA) on the hydrogen production of a single cell Proton Exchange Membrane (PEM) electrolyzer operated at room temperature and atmospheric pressure. In the first part of the thesis, the catalyst ink, without the metal catalysts, coated membrane (MEA), with the 16 cm2 active area, were produced. For the proton exchange membrane Nafion-117 membrane was used. An experimental design (Small Central Composite Design) was done in order to investigate the optimum preparation conditions (such as temperature, pressure and holding time in the hot press) for MEA of PEM electrolyzer. The responses were water vapor permeability and the surface resistance of the catalyst ink coating. The optimum conditions that gave maximum permeability and lowest surface resistance were found at 135°C of the hot press temperature, 5000 pound of pressure and 3 minute of holding time. In the second part, Membrane Electrode Assembly containing Pt and Pt/Ru metals in the catalyst ink was produced using the optimum conditions found in the first part. Then the prepared MEA was compared with the commercial MEA containing Pt and Pt/Ru metals using our home made single PEM electrolyzer.