A photogalvanic study of K3Mn(CN)6 in CN- aqueous solutions is reported. The appearance of an increasing current when the anodic solution containing the Mn(III) complex is irradiated with uv light, has been observed. This photocurrent attains a stationary value which remains constant for at least 6.5 h. Further, when the light is turned off, the current increases again up to a maximum value after which it decays exponentially. Simultaneously, hydrogen evolution has been observed in the cathodic compartment. In situ cyclic voltammetries were recorded in order to study the processes during electrolysis. A three step scheme is proposed that accounts for the experimental results. © 1990.