A mathematical model is presented for the electrodeposition of multicomponent alloys by an arbitrarily specified current source. The model takes into consideration transient, convective mass transfer to a rotating disk electrode, Butler‐Volmer kinetics, and individual component activities in the electrodeposit. The model can be used to calculate current‐potential relationships, ionic concentration profiles, and electrodeposit composition. Results for square‐pulse, pulse‐reversal, and triangular current waveforms are presented. An analogous model for potential‐controlled electrolysis is also discussed.