Benzyl methacrylate (BzMA) was graft copolymerized onto wool fibers by using ammonium peroxydisulphate as the initiator. Grafted samples with different polymer add ons (from 7 to 180%) were obtained by varying the monomer concentration in the reaction system. Following grafting with BzMA, the X-ray diffraction peak at 20.2Π slightly moved towards higher spacing values. Birefringence decreased, indicating a lower degree of molecular orientation of grafted wool fibers. The equilibrium regain values of grafted wool decreased with increasing add on. Tensile strength increased in the range 45-77% add on, while elongation at break decreased. Differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements showed a higher thermal stability for grafted wool. Following grafting, the drop of dynamic storage modulus (E) shifted to a lower temperature. Accordingly, the intensity of the loss modulus (EΠ) peak decreased, indicating that the thermally induced molecular motion was enhanced by grafting. Thermomechanical analysis (TMA) confirmed the increase in chain mobility for the grafted wool fibers. Above 35-40% add on, the presence of homopolymer on the surface of the wool fibers was identified by scanning electron microscopy.