By the action of a small amount of an acid, 2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane decomposed to give p-toluenesulfonic acid resulting in the proliferation of acid molecules. The decomposition manner was stepwise in solution state and autocatalytic in polymer film. The sensitivity of an acid-catalyzed photoimaging material was enhanced by 10 times upon the addition of the above compound due to the acid proliferation.