The development of a versatile mould with thermally separated heat cavities makes two-component (2K) injection moulding of ethylene-propylene-diene monomer (EPDM) with polyolefins possible despite the different temperature requirements for thermoset rubbers and thermoplastics. During processing a thermoplastic molten zone is created near the rubber/thermoplastic interface in the thermoplastic cavity, while vulcanisation occurs in the rubber cavity. Consequently and depending on the EPDM curing system, adhesion mechanisms like chemical bonding and/or interdiffusion may be initiated. For EPDM with a sulphur curing system, only interdiffusion between EPDM and thermoplastics like polyethylene or polypropylene is possible, whereas peroxide curing may induce a co-vulcanisation reaction. Furthermore, the extent to which chemical bonding and interdiffusion occurs may be influenced by changes in curing system composition causing crosslink density and reactivity differences near the interface. This study focusses on characterising the dominant adhesion mechanism and the interdiffusion width. Between EPDM and polyolefins carbon-carbon bonds may form, which are abundant in both materials, making it difficult to characterise chemical bonding. Therefore, contact angle measurements were executed at high temperature on vulcanised and unvulcanised rubber substrates to determine reactive wetting due to vulcanisation. Furthermore, with SEM-EDS the chemical composition near the interface was determined and line scans across the interface gave an indication of the interdiffusion process by following sulphur and filler amount.