7-Acyl- and 7,7'-acylditheophylline derivatives were prepared from the reaction of theophylline with acid chlorides. In addition, a novel synthesis of these compounds was developed, which proceeds through an acylonium ion generated under mild conditions. The physical properties and stability of the derivative of choice, 7,7'-succinylditheophylline, depend on the synthetic procedure employed. This compound is a useful controlled-release prodrug of theophylline.