A study has been carried out of the reduction at cathodes of graphite, gas‐baked coke, and lampblack of the following compounds: maleic acid, pyridine, acetophenone oxime, benzophenone oxime, diethylketoxime, benzenediazonium chloride, azobenzene, butyl disulfide, oxalic acid, methylene blue, and phenylthioacetamide in acid solution and of acetophenone oxime, diethylketoxime, potassium benzenediazotate, azobenzene, N‐benzohydrylideneaniline, and potassium glyoxylate in alkaline solution. Lactic acid was electrolyzed in an undivided cell between carbon electrodes.In general, cathodes of graphite were the most active. In some reductions other forms of carbon were equal in activity and in three they were more active than graphite as cathodes.