The vulcanization of epoxidized natural rubber, reinforced with commercial carbon fibres submitted to oxidative treatment which increases the superficial functionality of the fibres was studied. This treatment has an effect on both the form of the vulcanization curves in the rheometer and in the kinetics of the vulcanization. Similarly, the functionalization of the fibres produces a marked change in the distribution of the different sulphur type links. The bonds between the matrix and fibre are computed as interchain bonds, this produces a rise in the crosslink density.