The mathematical problem corresponding to a one-electron reversible electron transfer at a rotating disk electrode is solved under transient and steady state conditions by using the homotopy perturbation method. Analytical solutions for the time-dependent and stationary concentration profiles, current response and diffusion layer are deduced for finite values of the Schmidt number. The solutions enable us to obtain the response in chronoamperometry, normal pulse voltammetry and steady state voltammetry. The analytical results are assessed by comparison with previous analytical solutions for limiting cases as well as with numerical simulations, finding a satisfactory agreement.