The electricity production in PAFC(phosphoric Acid Fuel Cell) is accompanied by approximately equal amount of heat generation. For the best performance and efficient operation of the fuel cell stack, temperature distribution in the fuel cell stack should be controlled. Because the temperature gradient, both in the direction of stacking and in the cell plate, affects the cell performance, endurance, eletrolyte loss, and corrosion. In this study, a 30-plate phosphoric acid fuel cell stack was analyzed and modelled by using electrochemical equations and heat and mass transfer equations. To obtain more realistic profiles, local values of temperature and current density were used in the calculation. Obtained results agreed well with experimentally measured values : the temperature deviation from the measured values was less than 1.5℃.