Reduction mechanisms of a series of alpha-dicarbonyl compounds are studied in basic media. The electroreductions of 3,4-hexanedione, methylglyoxal and 1,2-cyclohexanedione are investigated through polarographic, voltammetric and kinetic studies. The effect of pH, reactant concentration and scan rate on the electrochemical parameters is studied. The results indicate that the two first compounds are reduced through CECE mechanisms where the rate-determining step is the second one-electron transfer, while the last compound is reduced through a CEC mechanism, where the rate-determining step is a protonation reaction placed after two reversible one-electron transfers. The influence of adsorption on the reduction of 1,2-cyclohexanedione is also studied. The results obtained here, together with those reported in the literature for other alpha-dicarbonyl compounds, are discussed and parallel electrochemical behaviour of these compounds is made evident.