SynopsisA number of α‐hydroxy acids, including glycolic, lactic (l(+) andd(–) forms) citric, hydroxybutyric and malic acids, were evaluated for their effects on various skin properties at concentrations of 0.5–1.15m. The acids were evaluated for their stinging potential on sensitive skin, the ability to increase skin cell renewal, and their ability to improve moisture content and reduce lines and wrinkles over a six‐week period. Results indicated that lacticl(+) and glycolic were the most effective acids when tested at equimolar concentrations. Both materials were less irritating than thed(–) lactic acid form and the other acids tested. Even though with long‐term use bothd(–) andl(+) lactic acid and glycolic acid produced comparative improvements in skin hydration and lines and wrinkle improvement, thel(+) form of lactic acid did so with fewer consumer complaints than any of the other acids tested. When the concentration of lactic and glycolic acids was increased to more than 1.5ma greater difference in irritation potential was observed with respect to stinging, with thel(+) form of lactic acid being less irritating than glycolic acid and thed(–) form. Our results suggest thatl(+) andd(–) lactic acid and glycolic acid are the two most effective materials for developing α‐hydroxy acid products. Lactic acid has a slight technical advantage over glycolic acid. Bothl(+) and thed(–) forms are better moisturizers when fully or partially neutralized. Moreover thel(+) form is also less irritating thand(–) and glycolic acid. Other acids such as citric, malic, and hydroxybutyric acids appear to be less effective materials but may be useful additions to lact