Large deviations from the behavior predicted by the Butler-Volmer equation of electrochemistry are accounted for using mesoscopic nonequilibrium thermodynamics. The nonequilibrium thermodynamic hypotheses are extended to include velocity space and cope with imperfect reactant transport leading to departures from Butler-Volmer behavior. This results in a modified Butler-Volmer equation in good agreement with 4D experimental data. The distinct advantages of the method and its applicability to analyze other systems are briefly discussed.