A model was developed to simulate the electrochemical behaviour of multistep electrochemical reactions involving diffusion and charge transfer control, fractional coverage of the electrode with the reaction product, and formation of a surface layer of electroactive compounds. Numerical calculations using this model were carried out to exploit the results of transient techniques. This procedure was used to study the mechanism of deposition of refractory metals, such as titanium and niobium. The reaction parameters of the multiple reaction sequences, standard potentials, diffusion coefficients, rate constants and saturation coverage, were calculated.