The present invention is directed to an improved copper plating bath for depositing a copper layer onto a printing cylinder, the copper plating bath comprising: (a) a source of copper ions; (b) a source of methane sulphonate ions; (c) a source of chloride ions; (d) an organosulphur compound having the formula R--S--R'--SO.sub.3.sup.-X.sup.+ or X.sup.+--O.sub.3S--R'--S--R--S--R'--SO.sub.3--X.sup.+, wherein R is alkyl, hydroxyalkyl or alkyl ether, R' is a C.sub.2 C.sub.4 alkyl group, and X.sup.+ is a cation; and (e) a polyether compound and method of using the same. The copper plating bath produces a plating deposit that has a stable hardness and is free from self-annealing during high speed plating.
