The change in rayon fibre properties due the grafting polymerization of methyl metacrylate (MMA) and butyl acrylate (BA) was investigated. The formation of rayon-g-PMMA or PBA was confirmed by FTIR spectroscopy, X-ray analysis, and TGA. The adhesion to PMMA and epoxy resin matrixes was determined using the microdrop technique. The PBA or PMMA grafting on the fibre led to lower mechanical properties than the ungrafted rayon fibre. However, the grafted rayon had better thermal properties than the ungrafted rayon and a shift of the decomposition temperature of the rayon was observed. The PMMA grafted to rayon improved the interfacial adhesion when PMMA was used as matrix (microdrop technique). The grafted polymer (PBA or PMMA) restricted the "wetting" of the fibre when epoxy resin was used as matrix and lowering the adhesion in comparison with ungrafted rayon fibre.