An efficient and selective electrochemical carboxylation process of some polychloromethanes was developed to synthesize chloroacetic acids using a zinc cathode and sacrificial anodes under a galvanostatic regime. The electrochemical behavior of carbon tetrachloride (CT), chloroform (CF), and its carboxylated products was studied by cyclic voltammetry in acetonitrile using tetrabutylammonium perchlorate as a supporting electrolyte in the presence and absence of CO2. Galvanostatic electrolyses of CT and CF in the presence of CO2 were carried out in an undivided cell. The influence of some operative parameters on the performance of the process was studied. The electrochemical carboxylation of CT resulted in high faradaic yields and in the selective formation of trichloroacetate (TCA). The electrocarboxylation of CF led to high current efficiencies and a good dichloroacetate yield. TCA and dichloromethane (DCM) were obtained as by-products in this process. The formation of TCA and DCM suggests that the electrocarboxylation reaction of CF competes with the self-protonation of the carbanion CHCl2- generated in its reduction process.