It was found that the change of vulcameter torque in the end stage of curing period of natural rubber does not follow first-order kinetics and can be expressed in a kinetic equation of 1/1-n (M-H - M-t)(1-n) = C - kt(n not equal 1). The reaction order n calculated by the above equation is in the range of 0.68-0.74. The rate constant of the end stage increases with a rise in temperature and is well satisfied with Arrherius equation, giving activation energy E = 79.321 kJ/mol. If whole curing period is treated by first-order kinetics without a change of reaction order from n = 1 to n = 0.68-0.74, the values of torque in the end stage of curing period predicted with first-order kinetics equation will be lower than that obtained from vulcameter. (c) 2006 Wiley Periodicals, Inc.