The hydrogen evolution reaction was studied on smooth electrodes of nickel + molybdenum alloys with atomic compositions equal to 0, 1, 3, 5, 10, 20 and 25% Mo in 2 M NaOH at 30 degrees C. The alloys were prepared by melting in an induction furnace and arranged as rotating disc electrodes. X-ray diffraction patterns indicate that these alloys are solid solutions with a f.c.c. nickel-rich structure corresponding to the ct phase. It has been determined that at low overpotentials (eta < 0.2 V) the electrocatalytic activity follows the order 25% Mo congruent to 3% Mo > 20% Mo congruent to 10% Mo > 0% Mo congruent to 1% Mo congruent to 5% Mo. In the high overpotentials region, the differences in the electrocatalytic behaviour are less significant, that of 25% Mo being the less active due to its high Tafel slope. The kinetic parameters of the elementary steps (theta(e), alpha, j(v)(0), m(H) corresponding to the Volmer-Heyrovsky-Tafel mechanism were evaluated starting from the dependences log j vs. g. From these values, the kinetic parameters of the net reaction were calculated and the results obtained were analysed and discussed.