Mechanisms implied in the electrocarboxylation of chloroacetonitrile (Cl-CH2-CN, noted RCl) mediated by [Co(II)(phen)(3)](2+) have been investigated by cyclic voltammetry and spectroelectrochemistry (UV-Visible and e.p.r.). The studies showed that the oxidative addition of chloroacetonitrile on the electrogenerated [Co(I)(phen)(2)](+) yields an alkyl-cobalt R-Co(III) complex. This complex can either be reduced into an alkyl-cobalt(II) or undergoes a homolytic cobalt-carbon bond cleavage to form the organic radical R- and the [Co(II)(phen)(2)](2+) complex. Whatever the process, R- and [Co(I)(phen)(2)](+) were produced. In presence of free phenanthroline, the catalytic behaviour of the complex was strongly vanished because the formation of the active complex [Co(I)(phen)(2)](+) is restricted. Under CO2 atmosphere, the catalytic electrocarboxylation of chloroacetonitrile was observed. Bulk electrolyses showed that the carboxylated and faradic yields depended on the applied electrolysis potential and free phenanthroline concentration. (C) 2013 Elsevier B.V. All rights reserved.