The effect of reaction condition on the grafting parameters during the grafting of methacrylamide (MAM) onto guar gum (GOH) using potassium peroxydiphosphate (PDP)-malonic acid (MA) redox couple has been studied. For higher grafting ratio and efficiency, the concentration of PDP and malonic acid should be above 2 x 10(-2) mol dm(-3) and between (5-6 x 10(-3)) mol dm(-3), respectively. The concentration of methacrylamide and hydrogen ion should be 20 x 10(-2) mol dm(-3) and 4.25 x 10(-2) mol dm(-3), respectively. Optimum temperature for grafting is 40 degrees C. As the time period of reaction is＇ increased grafting ratio increases. The plausible mechanism of grafting has been suggested.