The electrocatalytic oxidation of hypophosphite was studied in strong acid medium, at a nickel electrode, in the presence of different electrolytes (H3PO4. H2SO4, HNO3, and HClO4). A correlation was found between the effects of the anion electrolyte on the Ni catalytic activity and on the metal dissolution. These phenomena were explained in terms of the competitive adsorption between the anions electrolyte and H3PO2 species. The comparison of the Ni2+ amount in electrolyzed solutions containing hypophosphite and hypophosphite-free solutions showed that depending on the anion electrolyte, the presence of H3PO2 may accelerate or hinder the dissolution of the nickel electrode. Thr dependence of the Ni2+ amount on the hypophosphite concentration reveals that the H3PO2 species participate in the Ni dissolution. The effect of the electrolyte composition on the Ni catalytic activity was also analyzed in terms of pH medium in strong acid pH range.