A network model has been proposed in order to predict the gas velocity distributions in a PEFC It analyzes the gas-velocity distributions depending on the local pressure drop which is affected by the gas-flow rate and the water accumulation Liquid drop form was observed in a PEFC by using neutron radiography, and classified into two models The one is small liquid drop accumulated near the rib corner, and the other is larger drop which is generated to be combined with small drops Numerical simulations were carried out for obtaining the local pressure drop caused by a liquid drop, and correlation equations were obtained for the pressure loss coefficient