Retention of the water content of the membrane in the polymer electrolyte membrane fuel cell is critical for obtaining the maximum power density. Humidification of the reactants is a must to keep the membrane in a wet condition. The present paper identifies the parameters to achieve the maximum humidification of the reactants. Optimization of humidification is also discussed with respect to the pressure drop of the reactants while trying to achieve the theoretical relative humidity (RH), especially for the requirements of a multi-kilowatt stack.