Rotating disc electrodes are used to analyze electrochemical reactions in electrochemical cells and various rotating types of machinery. This model contains a system of fully coupled equations. This paper deals with EC′ reaction mechanism arises in Rotating disk electrode. This mathematical model contains system of reactionconvection-diffusion equations. Taylor series method is applied to find the analytical expression of concentration and current. The solutions enable us to obtain the current response in chronoamperometry and steady-state voltammetry and it is beneficial to study the behavior of the system. The obtained results are compared with the numerical simulation. An excellent agreement is observed between the series of solutions obtained by simulation solution. The effect of the parameters on concentration and current are discussed and presented graphically.