Quantitative data on the factors controlling the percentage composition of an electrically deposited alloy are meager, except for a few isolated binary and ternary systems. This study of the deposit obtained from the copper‐nickel system shows that : (1) the per cent of copper in the plate is always greater than that of the bath, the difference becoming progressively smaller as the copper content of the bath increases; (2) the ratio of copper to nickel on the plate increases linearly with the temperature; and (3) low current densities favor the deposition of high copper alloys. Increase in free cyanide content was found to decrease the rate of deposition, agreeing with the observations made by Kremann on the copper‐tin and copper‐antimony systems. Probable empirical equations to fit the data are given.