The cathodic behavior of cobalt, nickel, copper, and zinc complexes of 8‐hydroxy‐ quinoline‐5‐sulfonic acid, 1,10‐phenanthroline, glycine, 1,2‐ and 1,8‐naphthalenediamines, tetramethylethylenediamine, and dimethylglyoxime was investigated by determining cathode current efficiencies and polarograms. Deposition was not obtained from ions believed to have hybridized orbitals which involve the penultimate electron shell, that is, from the “inner orbital” complexes of Taube. Deposits were obtained from “outer orbital” ions, thus confirming the rule previously proposed. Evidence is given that copper, as well as cobalt and nickel, forms both types of ions.