Radiofrequency (RF) Ar/propylene glow discharge is utilized for grafting polypropylene onto muga silk yarn at working pressure of 1.2 x 10(-1) mbar and in the of RF power range of 20-80 W. The plasma discharge is diagnosed using self-compensated emissive probe to study the variation of ion energy impinging on the substrates with RF power. From chemical compositional analysis, a possible grafting mechanism between propylene and muga yarn is proposed by considering the charge-transfer initiation through the formation of electron-donor-acceptor (EDA) complex. X-ray photoelectron spectroscopy reveals that at RF power values of 60-80 W, the ion sputtering effect becomes dominant over plasma grafting thereby leading to severe destruction in chemical structure of the polypropylene grafted (PP-grafted) muga yarns. The experimental results show that PP-grafted muga yarns exhibit improved mechanical strength and hydrophobic behavior as compared to the virgin yarn. The properties of the PP-grafted muga yarns are observed to be dependent on atomic concentration, surface morphology as well as the results obtained from plasma discharge characteristics.