The scope of this study is to continue our earlier studies on the peroxide curing of diene elastomers. The effect of peroxide content and temperature on the curing and mechanical properties of NBR and H-NBR rubbers with different acrilonitrile content was evaluated. Experimental evidence indicates that saturated rubbers behave as expected whereas in unsaturated nitrile rubbers abstraction of allylic hydrogen and addition to the double bonds can act as mechanism of crosslinking, the weight of each mechanism is dependent of DCP content and curing temperature. The addition mechanism produces densely crosslinked zones or clusters, generating a heterogeneous network with effect on the vulcanizate properties. (c) 2006 Wiley Periodicals, Inc.