Catalytic mixed oxide electrodes of Ru/Ti, Ru-Sn/Ti, and Ru-Sn-Ti/Ti effective to destruction of refractory organics in aqueous waste were studied in views of their electrochemical properties and lifetimes. The electrochemical activity of the Ru-based mixed oxide electrode increased almost linearly to the amount of Ru included in the oxide layer, and it decreased rapidly at sintering temperature over 550℃ because of decrease of the degree of non-stochiometry within Ru oxide. The electrode roughness increased linearly with the electrochemical activity and the number of coating layers on electrode. The lifetime of Ru oxide electrode was the longest at the sintering temperature of 450 o C, and the sintering temperature did not affect lifetimes of Ru-Sn and Ru-Sn-Ti oxide electrodes. The lifetime of oxide electrode increased exponentially with the number of coating layers. The existence of Sn and Ti in the Ru-Sn-Ti oxide electrode generally had a bad effect on its lifetime. The electrochemical activity and the lifetime of Ru-Sn-Ti oxide electrode were the best at a specific ratio of Sn to Ti of 1.5.