Abstract: An article is zinc plated by electrodeposition in an alkaline zinc plating bath of ZnO and NaOH to which has been added, together with a small quantity of an aromatic aldehyde, a polyamine sulfone represented by the formula ##STR1## WHERE: EACH OF R.sub.1 and R.sub.2 is hydrogen, an allyl group, a straight-chain or branched-chain alkyl group having 1 to 16 carbon atoms, an aralkyl group, or a hydroxyalkyl group of the general formula HO--CH.sub.2).sub.m, where m is an integer of 1 to 6;X.sup.- is a halogen ion, HSO.sub.4.sup.-, HSO.sub.3.sup.-, HCOO.sup.-, or CH.sub.3 COO.sup.-; andn is an integer such that the number average molecular weight becomes 2,000 to 350,000.a and b are natural numbers having a relation such that a:b = 100; (10 to 100).