Electrodes constructed with different electroactive materials such as platinum (Pt), nickel (Ni), 304 stainless steel (SS) and low carbon steel (LCS) have been tested in water electrolysis using 1-n-butyl-3-methylimidazolium terrafluoroborate (BMI.BF4). All experiments were performed at room temperature using a classical Hoffman's cell operating at atmospheric pressure and at different cathodic potentials. For the electrodes were observed, with studied herein, in the presence of a 10 vol.% solution of BMI.BF4 in water, current densities (j) in the range 10-42 mA cm(-2) overall hydrogen production efficiencies (experimental/theoretical hydrogen production ratio) between 82 and 98%. The highest j values obtained with Pt, Ni, SS and LCS electrodes were 30,12, 10 and 42 mA cm(-2), respectively, and all efficiencies were in the 85-99% range. These comparative results show that the LCS electrocatalyst constitutes an attractive alternative for the technological production of high purity hydrogen by water electrolysis reaction since the LCS electrode gave j and efficiencies as high as those observed with platinum electrodes. (c) 2006 Elsevier B.V. All rights reserved.