This paper develops the theory for a pseudo-first order catalytic mechanism in chronopotentiometry with a power time current, I(t) ¼ I 0 t u (u ! À 1/2), applied to a spherical electrode of any size, and the advantages of the use of small electrodes and ultramicroelectrodes are discussed. The advantages of using a cyclic power time current to reach a stationary response suitable for characterizing a catalytic mechanism easily and accurately are reported. The reciprocal derivative (dt/dE À E) curves, which present peaks quantitatively related to the kinetic parameters of the chemical reaction, have been obtained from the potential-time responses. The influence of the homogeneous kinetic, the electrode radius and the power of time current in the achievement of a stationary response is analyzed. Methods for determining thermodynamic and kinetic parameters of the chemical reaction are proposed.