High-temperature molding of a mixture of epoxidized natural rubber (ENR) and intermediate super abrasion furnace (ISAF) carbon black results in strong rubber-filler interaction, the extent of which is greater in the case of the oxidized grade of the carbon black. It has been observed that ENR is bonded to the filler surface through the formation of primary bonds, such as ester and phenolic ether. An extensive filler-filler network formation takes place through the hydrogen bonding between the active groups of the rubber and filler surface.