Electroformed nickel-tungsten alloy with low internal stress has been obtained in a sulfamate solution by using organic imides namely bis(benzene-sulfonyl)imide and ortho-benzosulfimide as stress-reducing agents. Concurrently, the hardness of the alloy electroforms thus obtained was increased by these imides, especially the ortho-benzosulfimide. The effect of im ides on ha rd ness after thermal treatment of the alloy electroforms is also studied.