In dimethylformamide containing tetramethylammonium perchlorate, cyclic voltammograms for the reduction of 1,8-dibromo- and 1,8-diiodooctane and of 1,10-dibromo- and 1,10-diiododecane at glassy carbon electrodes exhibit single irreversible waves corresponding to cleavage of the carbon-halogen bonds. Controlled-potential electrolyses of 1,8-dibromo- or 1,8-diiodooctane at reticulated vitreous carbon result in the formation of n-octane, 1-octene, and 1,7-octadiene as the principal products; in addition, significant amounts of n-hexadecane are observed when 1,8-diioodoctcane is electrolyzed. Similarly reduction of 1,10-dibromo- or 1,10-diiododecane leads to the production of n-decane, 1-decene, and 1,9-decadiene, with n-eicosane being another species derived from 1,10-diiododecane. From the coulometric data and product distributions, along with information gained from experiments done in the presence of deuterium-labeled reagents, we conclude that the reductions of 1,8-diiodooctane and 1,10-diiododecane involve both radical and carbanion intermediates, whereas only carbanions are important in electrolyses of 1,8-dibromooctane and 1,10-dibromodecane.