A conventional vulcanization system containing tetrabutylammonium bis(4-methylphenyldithiocarbimato)zincate(II) (ZNIBU) was used for curing of natural rubber (NR) compounds. Rheometric (t(s1), t(90), and CRI) and mechanical properties, such as tensile and tear strengths and modulus at 300%, were measured to evaluate the acceleration potential of ZNIBU. Commercial accelerators (TMTD, MBTS, and CBS) and a binary system CBS/ZNIBU were also tested for comparison purposes. It was observed that ZNIBU alone does not give either safe scorch time or cure rates appropriate for industrial applications. Nevertheless, mechanical properties are comparable to those given by the other accelerators used. As for the binary system, positive synergistic effects can be found in tear strength and modulus of NR vulcanizates. Besides, ZNIBU does not contribute for the formation of nitrosamines in the vulcanization process. (c) 2008 Wiley Periodicals, Inc.