In this study the possibility to increase the productivity of acid cation-exchange resin catalysts active sites in ETBE synthesis was elucidated. For this purpose the inorganic-organic sulfonated cation-exchange resins with different polymer loadings (1.5-9.2 wt.%) have been synthesized. Such polymer/carrier composites as well as commercial acidic microporous gel-type ion-exchange resin KU-2-8 and macroporous Amberlyst 15 have been studied in the ETBE synthesis. Acid properties of all solids were determined by quasi-equilibrium thermogravimetry of ammonia desorption. We have found out that polymer loading and acid capacity affect oppositely on the ETBE productivity. As a result, there is no direct correspondence between the ETBE productivity of the inorganic-organic sulfonated cation-exchange resins per gram of catalyst on their acidity. However, there is a linear relation between the productivity per gram of polymeric phase and acidity. It was established that due to a better accessibility of acid sites for reactants loaded sulfonated cation-exchange resins exceeds the commercial catalysts by the site time yield values. (C) 2009 Elsevier B.V. All rights reserved.