A silver and silver
alloy plating bath, includes (A) a soluble salt, having a silver salt or a mixture of a silver salt and a salt of a
metal such as
tin,
bismuth,
indium, lead, and the like; and (B) a particular aliphatic
sulfide compound, such as thiobis(diethyleneglycol), dithiobis(triglycerol), 3,3′-thiodipropanol, thiodiglycerin, 3,6-dithiooctane-1,8-
diol, and the like, which contain at least one or more of an
ether oxygen atom, a 1-hydroxypropyl group, a hydroxypropylene group, or two or more of a
sulfide bond in the molecule, and not containing a basic
nitrogen atom. Compared to baths containing aliphatic monosulfide compounds, such as
thiodiglycol or beta-
thiodiglycol, which do not contain an
ether oxygen atom, 1-hydroxypropyl group, a hydroxypropylene group, or two or more of a
sulfide bond in the molecule, by having these particular compounds, the plating bath of the present invention has excellent stability over
extended time, excellent co-deposition of silver and various metals, and excellent appearance of the electrodeposition
coating.