Precuring of one of the blend components is a promising strategy in order to improve the mechanical properties of elastomer blends and thereby broadening their application spectra. In the present work, the effect of precuring chlorobutyl (CIIR) on the properties of its blends with ethylene-propylene-diene monomer rubber (EPDM) is discussed. The optimum precuring that has to be given to the CIIR phase was determined on the basis of the variation of blend mechanical properties. It was observed that without affecting the processing safety of the blends, precuring of the CIIR phase substantially improves the mechanical properties of EPDM/CIIR blends as compared to their conventionally cured blend counterparts. Morphological studies using scanning electron microscopy substantiate the results.