Disclosed are 3-aryl-2-cyano-3-hydroxy-acrylic acid derivates of formula, R1 is hydrogen, C1-C20alkyl; C1-C20alkoxy; CF3; C6-C10aryl; or a radical of formula (1a), ; and R2 is hydrogen; or C1-C20alkyl. The compounds are used as antimicrobial actives for the treatment of surfaces.