ABSTRACTThermoplastic vulcanizates are prepared by blending ethylene–octene copolymer with polydimethylsiloxane rubber and dynamically cross-linking with dicumyl peroxide. From moving disc rheometer study, it is found that, as the octene content increases, the cross-linking efficiency of the peroxide to cross-link that particular ethylene–octene copolymer decreases. For ethylene–octene copolymer 8445 thermoplastic vulcanizates, as the blend composition changes from 50:50 to 80:20 ethylene–octene copolymer:polydimethylsiloxane, there is 116% increase in tensile strength which is correlated with the morphology study by atomic force microscopy. All the different ethylene–octene copolymer:polydimethylsiloxane thermoplastic vulcanizates exhibited lower dielectric constant and higher electrical resistivity which makes it suitable for the cable insulating applications.