The frictional pressure drop characteristics in gas channels of Polymer Electrolyte Fuel Cells (PEFCs) are modelled in this work. The two-phase flow in gas channels of PEFCs has its special features: (1) combination of reactant gas, water vapor and liquid water, (2) flow in micro/mini channels, (3) reactant consumption, (4) condensation from water vapor, (5) continuous water introduction from reaction and (6) flow pattern transitions. Therefore, previous two-phase pressure drop correlations, primarily for adiabatic gas liquid flow, might not be able to capture the pressure drop in the gas channel with a porous wall. The new flow pattern based pressure drop method covers three major flow regimes in gas channels, i.e., the single-phase gas flow zone, and droplet/mist flow and slug/film flow in the two-phase flow zone. In the droplet/mist flow regime, a homogeneous flow modelling was adopted, while in the slug/film flow regime, a modified Chisholm value of 8.5 was used. The new predictive tool presents improved accuracy in pressure drop estimation for different current densities and stoichiometric ratios of operating PEFCs.