The influence of silane coupling agent on properties of silica-filled compounds under peroxide curing was investigated. bis (triethoxysilylpropyl) tetrasulfide (TESPT) was selected in this study and its content was varied from 0 to 12% w/w of silica. It is found that with increasing TESPT content, bound rubber content, tensile strength, elongation at break and tear strength are enhanced. By contrast, magnitude of Payne's effect, modulus at 100% elongation (M-100) and heat build-up are decreased. The changes of such properties are attributed to the reduction of crosslink density in conjunction with the improvements of both rubber-filler interaction and degree of filler dispersion with increasing TESPT content in the peroxide curing system. POLYM. ENG. SCI., 59:42-48, 2019. (c) 2018 Society of Plastics Engineers