The electroreductions of 8-quinolinecarboxylic acid and his derivative quinmerac (a quinolinic herbicide) are studied by cyclic and differential pulse voltammetry on mercury electrodes. The use of surfactants was found essential to avoid the adsorption of reactants on the mercury surface. In both cases the electroreduction processes corresponded to electrodimerization reactions in competition with ECE processes, depending on the experimental conditions. The oxidation of the radicals formed after the first electron transfers differ from 8-quinolinecarboxylic acid to quinmerac, being more complicated in this last case. (C) 2012 Elsevier Ltd. All rights reserved.