comprised of iridium oxide over titanium metal has unexpectedly been found to have a life span in excess of 1000 hours while other dsa type anodes failed in less than 15 hours of operation a an iridium oxide over titanium anode dsa was placed in a beaker containing a 20 h 2 so 4 solution and electric current dc was passed through it at a current density of 340 amps per square foot the electrolyte bath was maintained at an accelerated test temperature of 50 u00b0 70 u00b0 c which is somewhat higher than the normal operating temperature of less than about 50 u00b0 c an aluminum sheet which acts as the cathode in the liquid contact cell was immersed in the electrolyte the anode failed after 1356 hours of continuous use when peeling occurred at an operating temperature of 30 u00b0 c the anode was still active after 6 months no significant level of contamination was found in the electrolyte either under the accelerated test or the operating temperature conditions furthermore no corrosion and errosion was noted on the indium oxide coated anode b anodes comprised of 1 platinized tantalum 2 platinized niobium columbium 3 30 iridium 70 platinum alloy coated on titanium 4 30 iridium 70 platinum alloy coated on tantalum and 5 ruthenium oxide over titanium were substituted for the iridium oxide over titanium anode of run a and anodization carried out under the same operating conditions with the following results ______________________________________anode life span hours______________________________________1 62 2 53 144 125 less than 2______________________________________ at the operating temperature of about 30.