The use of formic acid as a hydrogen-storage material has become more feasible thanks to the development of a homogeneous catalytic system of ruthenium water-soluble complexes (Ru/TPPTS; TPPTS=meta-trisulfonated triphenylphosphine) that selectively decomposes HCOOH into H2 and CO2. Continuous generation of H2 of very high purity, over a wide range of pressures, and under mild conditions was achieved.