A fuel cell can be considered a continuously an electrochemical generator of electric power by converting the chemical energy of its reactants directly into electricity and heat, without combustion. A cell consists of two electrodes (porous structure) separated by an electrolyte, which is an easy transfer medium for ions (ion conductor). Fuel cells convert fuel energy into electricity through electrochemical reaction. A gaseous such as hydrogen is introduced to one side of the cell and oxygen to another. A reactant concentration gradient across the cell yields a potential difference between the electrodes. At the anode, hydrogen is oxidized, or stripped of electrons. By the potential difference between the electrodes, the electrons flow in the external circuit. Meanwhile, ions moving through the electrolyte balance the charge flow in the external circuit. At the cathode, oxygen accepts electrons coming from the anode via the external circuit. This acceptance of electrons, known as reduction, forms negatively charged oxygen ions. The amount of direct current electricity produced by electron flow from anode to cathode depends on the chemical activity and the amount of substance supplied and the loss of power in cell stack. The remaining inefficiencies produce waste heat that must be rejected to keep the PEMFC system at its optimal temperature. The common methods for heat rejection are air-cooling, liquid-cooling as water or ethylene glycol combination with water. The coolant can come in contact with the Pt if the cell compartment is not sealed properly, or there are leaks through electrocatalysts