Combined voltammetry and potentiostatic transient techniques have been used to study nucleation, formation and growth of thin oxide films on high purity polycrystalline bismuth in a berate buffer solution, pH = 9.2. It was shown that the initial step in the formation of the continuous anodic layer of bismuth oxide on bismuth is a nucleation process. The potentiostatic technique was a valuable tool in its study. The oxide him nucleation kinetics were explained reasonably well through a 3D progressive nucleation and growth mechanism under diffusion controlled growth. Nucleation potential (E-AN), steady-state nucleation rate (AN(0)) and the number density of growing centre (N-s) are determined. A detailed mechanistic interpretation of the nucleation process and thickening of the anodic layer under potentiodynamic conditions was obtained using the criteria of cyclic voltammetry.