The effect of reaction conditions on grafting parameters during the grafting of ethyl methacrylate (EMA) onto polyvinyl alcohol (PVA) using eerie ammonium sulfate (CAS) initiator has been studied. The grafting efficiency (GE) was found to be optimum at a particular level of EMA, CAS,PVA,H2SO4, temperature and time. Acid hydrolysis and infrared spectroscopy (IR) were used for the confirmation of graft copolymer formation. The X-ray diffraction (XRD) pattern and thermogravimetric analysis (TGA) of PVA and a representative graft copolymer were studied. The plausible mechanism of grafting has been suggested.