Reaction kinetics of carboxymethylation of cornstarch in the reaction media of ethanol was studied in this article by determining the changes of NaOH concentration and degree of substitute of reacting matter in the reaction process at different temperature. The equation of reaction rate has been set up and proved to be corresponding with the second-order reaction. The main and side reaction rate constants at different temperature and the main and the side reaction activation energy have been obtained, respectively. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:1901-1907, 2011