Diepoxy vulcanization system of 1-chlorobutadiene-butadiene rubber (CB-BR) having hydroxyl groups with diglycidyl ether of bisphenol A (DGEBA) was studied in the presence of acid anhydrides. Phthalic anhydride (PAn), hexahydrophthalic anhydride (HAn), maleic anhydride (MAn), and succinic anhydride (SAn) were investigated as cocuring agents. The results of this investigation indicated that the hydroxyl groups attached to the polybutadiene backbone react with DGEBA to afford a CB-BR vulcanizate. The vulcanization rate depended on the kinds of acid anhydrides in the following order : PAn > MAn > SAn > HAn. It is assumed that the reaction between the hydroxyl group in CB-BR and acid anhydride was the rate-determining step. The vulcanization of CB-BR with a higher amount of DGEBA afforded resinous rubber vulcanizates. Thus, DGEBA was concluded to act not only as a curing agent, but also as a reinforcing agent for CB-BR.