Abstract: Potentiostatic method is mainly used to study the nucleation and growth of molybdenum and their effects on electroplating. It has been shown that the rate-determining step of cathodic reaction in the initial stage is hemispherical nucleation with diffusion controlled growth and the quality of electroplates can be improved by controlling the factors effecting this step. Increase of applied overpotential results in increase of nucleus density rapidly, which is favourable for getting an electroplate with coherent nature.fine grains and smooth surface. Under constant potential a higher temperature leads to a higher nucleus density, which is in favour of electroplating. Increase in concentration of molybdenum usually leads to decrease of nucleus density whether Constant potential or constant current is kept in the electroplating.