Porous polymer films have been prepared from poly(butyl methacrylate) latex particles with surface sulfonate groups and been shown to retain up to 90% of the catalytic capacity of the original latex particles. Advantages of latex films over latex particles as reactive surfaces include easier removal from the reaction medium and easier cleaning/rejuvenation of the polymer films. The films have been characterized by specific surface area, mercury porosimetry, and conductometric titration. Reactivity was evaluated for the acid-catalyzed hydrolysis of ethyl methanoate.