The present paper shows the effects of reaction temperature on the activity and chain-transfer properties of all three starch branching enzyme (BE) isozymes, BEI, BEIIa and BEIIb, from rice towards amylopectin as a glucan substrate. The activity of BEI increased with an increase in the reaction temperature from 10 to 30ºC, then the activity decreased at higher temperatures, and finally BEI lost its activity at 45ºC. Both BEIIa and BEIIb activities were optimum at 25ºC, and no significant activity was found at 45ºC. The decrease in the enzymatic activity at high temperatures between 35-40ºC was more significant in BEIIb than in BEIIa. Despite the temperature-dependent activity, no practical changes in distinct chain preferences of any of the three BE isozymes were found. These findings indicate that these responses could influence the starch production, structure and physicochemical properties affected by environmental temperatures during the growth of rice plants.