The electroreduction of the NAD(+) model compound N’-methyl nicotinamide has been studied in acidic media (5 M H2SO4 to pH 5) by de and DP polarography and linear-sweep cyclic voltammetry. Tafel slopes and reaction orders were obtained from I-E curves traced at potentials corresponding to the foot of the polarographic wave. The protonation pK of the heterocyclic nitrogen was obtained from spectroscopic (UV) and potentiometric measurements, having a value of 3.50 +/- 0.15. Controlled-potential electrolysis indicated that at pH < 2.5 two electrons are transferred per reactant molecule and that the carbonyl group is reduced to hydroxyl. The reduction pathway consists of the reversible transfer of an electron and an Hf ion followed by an irreversible one-electron transfer, which is the rate-determining step, in agreement with what occurs in the reduction of NAD(+) coenzyme at these pH values.