The solubility of tetramethylammonium hydroxide pentahydrate in dimethyl sulfoxide is significantly increased by adding to the solution a quantity of dipropyleneglycol monomethylether. This permits up to twelve percent of the tetramethylammonium hydroxide pentahydrate to be dissolved in dimethyl sulfoxide, rather than the maximum of two percent that would otherwise be the case, which enhances the capacity of the solution to strip photoresist. Particularly, if the concentration of dipropyleneglycol monomethylether is in the range of ten to thirty percent, one can obtain both a high stripping rate and a much higher stripping capacity. For example, stripping capacity may be increased from one hundred forty substrates per gallon to six hundred substrates per gallon.