The degradation of the electrochemical reaction of the proton exchange membrane water electrolysis (PEMWE) can be characterized using in-situ current mapping measurements (CMM). CMM is significantly affected by the amount of clamping pressure and method. In this work the current is mapped downstream at the cathode side of 50 cm² active area single PEMWE cell at different clamping pressure and different clamping methods. Two clamping methods are used; bolting the cell with 8 bolts around the active area and clamping the cell from the whole area of the end plate using highly pressurized clamping set-up. CMM is carried out using S++ setup, where the segmented plate is placed between the current distributor and flow field plate downstream at the cathode side of the PEMWE cell. The segmented plate consists of 100 segments over the 50 cm², thus each segment area is 0.5 cm².

Initial results show that, the clamping pressure effect on the CMM is not symmetrical in both clamping method and it directly affects the CMM homogeneity. Also it is concluded that higher PEMWE cell performance not necessary means more homogeneous CMM over the cell area.