At normal operating temperatures (below 100 °C), the water in the proton exchange membrane fuel cell (PEMFC) is in the form of a mixture of gas and liquid phases. The content of water guarantees that the membrane has good proton conductivity, but it may also block the transmission of the reaction gas to the catalytic reaction sites. Based on the single straight channel of the PEMFC, the water content of the model at various voltages and the water distribution of the different parts are studied. The results indicate that the amount of water in the model generally increases with the reduction in the voltage. When the voltage is set from 1.1 V to 0.7 V, the increase in the amplitude of the water content is higher than 0.7 V–0.4 V, and the water content is highest at 0.5 V. Under each voltage, the largest water content occurs in the gas diffusion layer, the second one occurs in the channel, the third one occurs in the proton exchange membrane, and the water content in the catalyst layer is lowest.
