Theory is developed for heterogeneous ECE reactions occurring at channel electrode that predicts the voltammetric waveshape, as characterized by the half-wave potential and the Tafel slope as a function of the rate of mass transport and the cell geometry. Working surfaces are reported that allow the ready mechanistic interpretation of experimental data and the deduction of corresponding rate constants. Experiments are reported on the reduction of nitromethane in aqueous buffered solution (7 < pH < 9) at platinum electrodes that is thought to proceed via a heterogeneous ECEEE mechanism. Analysis of both waveshape and limiting current data confirm this mechanistic assignment, allowing the following appropriate kinetic parameters to be reported : heterogeneous rate constant, 0.26 +/- 0.07 cm s(-1); and standard electrochemical rate constant, 0.13 +/- 0.01 cm s(-1).