Tungstate ion reduction was studied in 1mol·dm-3 KCl or 0.5mol·dm-3 citric acid solutions using DC polarography. In citric acid solutions containing only tungstate ions, a tungstate ion reduction wave was observed only at 3.5 pH. This wave disappeared when cobalt ions were added to the solution because the hydrogen evolution current increased. Polarograms from KCl solutions containing only tungstate ions showed a well-defined tungstate ion reduction wave when the solution's pH was from 3.2 to 3.9. A clear tungstate ion reduction wave preceded by a cobalt deposition wave appeared in the KCl solution containing tungstate and cobalt ions at 6.0pH, but no reduction wave was obtained in the solution without cobalt ions. The limiting current for the tungstate ion reduction was proportional to that for the cobalt deposition, when the concentration of cobalt ions was lower than that of tungstate ions. This linear relation suggests that cobalt deposition induces tungstate ion reduction.