A hydrogen pump-type hydrogen sensor cell has been developed for continuously detecting a trace amount of impurities contained in hydrogen fuels, by using the impurity poisoning effect of PEFC-type electrochemical cells. The impurity-sensitive sensor cell was produced by extremely reducing Pt catalyst loading in order to detect even a small amount of impurities. This type of sensors with the stable baseline can detect major hydrogen fuel impurities, CO, H2S, and NH3, with the ppm-level detection limit. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.