Methods of eliminating spores of spore forming bacteria from the genus Clostridium on a surface comprise contacting the surface with an effective amount of an acidic aqueous composition having an acidic pH of from about 1 to about 4 and comprising from about 100 to about 2000 ppm dissolved chlorine dioxide, and a surfactant system having wetting effect and a spore solubilizing effect. The surfactant system comprises at least two hydrocarbon ionic surfactants stable for oxidation at the acidic pH, of which at least two surfactants have a difference in hydrocarbon chain length of at least four carbon atoms.