The kinetics of addition reaction of diethylamine to vinyl groups of oligo[(2-acryloyloxy-5-methyl-1,3-phenylene)methylene] in benzene with excess amine in the presence of lithium diethylamide as catalyst has been investigated. The reaction rate, was found to be expressed as: V = k [CH2=CH-][Et2NLi] with the ratio of [Et2NH]o to [Et2NLi]o being 5. Second-order rate constants for addition and the activation energy have been determined.