A method for point-of-use generation of chlorine dioxide wherein the chlorine dioxide is generated quickly and at acceptable concentrations to avoid the need for subsequent dilutions and keeping the product non corrosive to the surface to be treated. A persulfate solution and a chlorite solution are mixed at a molar ratio of persulfate to chlorite of greater than 2. The chlorite solution is buffered to a pH of from 9 to 12. The persulfate solution is buffered to a pH of from 3 to 9.