This paper presents voltammetric (linear-sweep cyclic voltammetry) and chronoamperometric studies on the electroreduction of 3,5,6-trichloro-4-methylpyridine-2-carboxylic acid (3CMPA) on mercury and carbon electrodes. The dissociation constants of 3CMPA were obtained from UV-vis spectra. The pK values were 1.7 +/- 0.1 (-COOH group) and 4.1 +/- 0.1 (pyridinic nitrogen). The electrochemical studies were performed in the acidity range 6 M H2SO4 to pH 7. Above the last pH value no signals were obtained. 3CMPA is adsorbed on the mercury electrode via a nucleation and growth process but no monolayer is formed in the accessible experimental conditions. From the voltammetric results in the carbon electrode, reaction pathways are proposed. (c) 2013 Elsevier Ltd. All rights reserved.