For polymer electrolyte fuel cell (PEFC) systems in vehicle applications, removal of external humidifiers from the cathode is desirable to reduce system efficiency, cost, space and weight, and thus PEFCs should achieve continuous self-humidification operation under cathode-dry conditions. A critical index to judge the success or failure of self-humidification is net water drag coefficient (alpha(NWD)). Self-humidification operation requires alpha(NWD)to be negative. Here, alpha(NWD) is experimentally evaluated using cells with different configurations of gas diffusion layer (GDL), membrane, and flow channel geometry. Experimental results confirmed that alpha(NWD) remains negative under cathode-dry conditions at a cell temperature of 60 degrees C, and that current density - net water drag coefficient (i - alpha(NWD)) characteristics are immune to configurations compared with the cell performance, when the flow rate of air at the cathode is low enough to keep alpha(NWD) low. In addition, under these conditions, the effect of flow velocity and pressure on the i - alpha(NWD) characteristics was limited. On the other hand, as expected, a thinner membrane promotes back-diffusion of water to the anode. In conclusion, the flow rate of air should be determined carefully so that the cell performance is maintained while self-humidification is achieved. (c) 2019 The Electrochemical Society.