DSA(R) type electrodes of ruthenium-manganese mixed oxides (30 less than or equal to at % Ru < 100) supported on titanium were prepared by the spray-pyrolysis technique, using Ru(NO)(OH)(x)(NO3)(3)-x and Mn(NO3)(2) as precursors. Electrodes were characterized by SEM, XRD and cyclic voltammetry. Their behaviour as anode for the chlorine and oxygen evolution reactions was also evaluated by polarization curves. The stability of the mixed oxides was determined through accelerated tests of service life. It has been verified that the best performance on the apparent electrocatalytic activity of both reactions as well as on stability is achieved at a composition of about 70% Ru.