Often, proton exchange membrane fuel cells performance are evaluated by polarization curves. A plot of cell potential against current density under a set of constant operating conditions, known as a polarization curve. An ideal polarization curve has three important areas: activation polarization, ohmic polarization and concentration polarization. In fact, these three types of polarizations are the cause of decrease in actual cell voltage from the theory irreversible quantity. For each area there are a few equations. In leatratures several semi-empirical equations were introduced to discribe the cell polarization behavior. Some of them were unable to foresee whole areas of the curve especially at high current density region. In this study twelve series of cell polarization curves under different operation conditions were examind by mentioned semi-empirical equations and four new suggested equations. These equetions were fitted to I-Vs better than semi-empirical equations specially at high current density region. The avrage error changed between (0.5 % to 1.4% ) for new equations versus (0.5% to 7% ) for semi-empirical equations.These equations have been built up by changing in equation (2-11) and the equation (2-17) was able to predict experimental data better than others with average error about 0.5% .Although equation (2-17) predicts data as well as equation (1-16) does , it has some more advantage than equation (1-16) such as including temperature , limiting current density, number of electron and Farady constant instead of constant parameters (m, n) .