The aim of this paper is to analyse loss characteristic of a high-pressure electrolyzer system for hydrogen production. Fundamental thermodynamics and electrochemical relations related to polymer electrolyte membrane (PEM) electrolyzer have been modelled in MATLAB. Simple proton exchange membrane water electrolysis is analysed on the basis of well-known Butler-Volmer kinetic for the electrodes and transport resistance in the polymerelectrolyte. The overpotential at the anode, cathode and overpotential due to ohmic resistance were analysed individually. A sensitivity analysis was carried out to study the effect of exchange current density on Faraday efficiency. At current density of 0.2A/cm2, a higher efficiency of 87.8 % was observed.