The electroreduction of nitromethane in aqueous solution is shown to follow a mechanism of the heterogeneous ECEEE type on gold electrodes as also seen for platinum and other substrates. Moreover, the rate of the chemical step is surprisingly similar, to within less than an order of magnitude, on all surfaces studied. Kinetic isotope measurements show that the chemical step in the reaction sequence is approximately a factor of 2 slower in D2O than in H2O. A mechanism is proposed that accounts for the lack of surface sensitivity and for the observed isotope effect.