p-Aminobenzenesulfonic acid is a potential impregnant on activated carbon for the chemisorption of acetaldehyde vapor. However, because of its low solubility in water, it is difficult to prepare the impregnated activated carbon with a high concentration of p-aminobenzenesulfonic acid. In the present work, activated carbons impregnated with various p-aminobenzenesulfonic acid salts were prepared by soaking three types of activated carbon in aqueous Solution of p-aminobenzenesulfonic acid with various alkali compounds as solubilizing agents. Ammonium hydrogen carbonate was found to be the most Suitable solubilizing agent for the impregnation or p-aminobenzenesulfonic acid. Alkali metal hydroxides reacted with p-aminobenzenesulfonic acid forming p-aminobenzenesulfonic acid alkali metal salts which had no reactivity with acetaldehyde, whereas ammonium hydrogen carbonate produced p-aminobenzenesulfonic acid ammonium salt which had high reactivity with acetaldehyde following the same stoichiometry as that of p-aminobenzenesulfonic acid.