The diffusion of amine stabilizers in vulcanized natural rubber formulations used in tires was investigated. Experiments were undertaken using a "sandwich" system composed of a sample disk containing the additive (source disk) between two external disks of nonadditivated rubber (reception disks). Diffusion coefficients (D) were calculated from the experimental migration curves following the Boltzman-Matano model. Theoretical diffusion curves for the additives were obtained according to the limited extension source in an infinite medium. Experimental data showed reasonable fitting with the theoretical curves, suggesting that D does not depend on the additive concentration. Thermooxidative stability data for the vulcanized rubber containing the additives showed no correlation to the diffusion process. (C) 2000 John Wiley & Sons, Inc.