A HCOOH (formic acid) hydrogen generator with a Pd/C3N4 nanocatalyst and a small amount of water was investigated for mobile PEMFCs (proton exchange membrane fuel cells). The catalyst produced hydrogen from HCOOH effectively, owing to high activity and selectivity. The HCOOH hydrogen generator was also evaluated in a hydrogen generation test for 3 h. Although 98 wt% HCOOH was directly supplied to the hydrogen generator, catalyst poisoning was prevented owing to a small amount of water. The conversion efficiency of the hydrogen generator was 95.5%, and less than 10 ppm carbon monoxide was produced from HCOOH dehydrogenation. The characteristics of HCOOH were compared with those of sodium borohydride solution, gaseous hydrogen, and liquid hydrogen. The HCOOH hydrogen generator has many advantages such as high conversion efficiency, high energy density, low hydrogen production cost, and relatively long storage duration. Consequently, the HCOOH hydrogen generator can be used for mobile PEMFCs. (C) 2016 Elsevier Ltd. All rights reserved.