Formic acid crosslinked epoxidized natural rubber (FC-ENR) with precrosslinking epoxide level of 33 mol% was prepared and compounded without any further curative and in blends with unmodified natural rubber. A total of four different materials—FC-ENR, NR, FC-ENR/NR blend (25/75) and FC-ENR/NR blend (50/50)—were prepared for analysis and designated mixes K, L, M and N, respectively. All the materials were ISAF black filled at 30 pphr loading. With the exception of the unblended FC-ENR the rest of the materials were cured using the semi-EV system. The unmodified NR vulcanizate served as control. In the present communication we report the results of our studies in the physical properties of the aforementioned vulcanizates. FC-ENR was found to have potential as an effective modifier for natural rubber.