Pulse plating of Ni-Mo alloys from nickel-rich electrolytes was studied with an inversed rotating disk electrode. The deposit composition and the current efficiency were measured as a function of pulse variables (pulse period, duty cycle) and mass transport parameters (electrode rotation speed, molybdate concentration). At sufficiently short pulse periods, the Mo content of the pulse plated alloys was higher than in dc plating. Experiments using a rotating electrochemical quartz crystal microbalance and Auger electron spectroscopy showed that under the conditions of the experiments no significant corrosion reaction takes place during the pulse off-time. A simplified non-steady state diffusion model can explain the observed enhancement in Mo content and correctly predict the influence of pulse plating variables on deposit composition.