A novel design of reference electrode was developed to in-situ measure the polarization of direct methanal fuel cell(DMFC).The effect of humidification conditions of electrolyte on the reference electrode potential and its potential stability was investigated.The experiment results showed that the potential of reversible hydrogen electrode (RHE)

acting as the reference electrode of DMFC

decreased with increasing degree of electrolyte humidification.It was found that the potential stability of RHE was mainly determined by the stability of its surface state.To obtain stable and accurate polarization curves

it was suggested that the electrolyte located on RHE should be humidified by liquid water on its opposite side and the flow rate of H2 should be controlled at an appropriate and stable value.