A one-compartment membrane-less electrochemical H-2 generator from borohydride was realized using a Rh porphyrin and RuO2 as the anode and cathode, respectively. H-2 generation from this cell was successfully controlled electrochemically by varying the potential applied. The regulation of H-2 generation was based on the selectivity of the anode and cathode. We found that RuO2 exhibits H2O electro-reduction activity without electro-oxidation or chemical decomposition of borohydride, and used the catalyst as a selective cathode in the electrochemical H-2 generator. Anode and cathode potentials of the electrochemical H-2. generator were measured separately. The both potentials were discussed in terms of the catalytic activities of a Rh porphyrin and RuO2. (C) 2009 Elsevier B.V. All rights reserved.