A detailed analysis of potential versus time measurements at galvanostatic charge/discharge conditions (external current change from -1 to +1 mA cm(-2)) for two La-Ni alloys in Ar-saturated 0.1 M KOH solution is presented. It is shown that passivation of the electrodes does not affect the potential jump as a result of current switching over. The value of potential jump allows to calculate the exchange current density for H2O/H-2 system on the tested material. Anodic potential of the hydrogenated electrode (at i(a) = const) linearly increases with logarithm of time which allows to evaluate precisely time necessary for oxidation of hydrogen absorbed during cathodic charging. The method described enables to determine effectiveness of hydrogen absorption by materials applied for negative electrodes of NiMH batteries.