We report several series of single perturbation experiments in the Belousov-Zhabotinsky (BZ) reaction which have been carried out by applying an electrical current to a platinum electrode in the continuous flow stirred tank reactor (6.4 mL). When a single short current pulse is applied at the maximum of a chemical oscillation (high Ce4+ concentration) or at the minimum (low Ce4+), the response is a small advance or a significant delay of the original phase of oscillation (negative or positive phase shift), respectively. Thus we obtain phase response curves as a function of electrical current strength and duration of the pulses. These results show that the redox reactions occurring at the platinum electrodes involve mainly the Ce3+/Ce4+ redox couple as supported by pulsed additions of known Ce4+ solutions. Numerical simulations are in good agreement with the experiments.