The effect of reaction conditions on the grafting parameters during the grafting of acrylamide (ACM) onto guar gum (GOH) by using a Cu+2-mandelic acid (MA) redox couple was studied. On increasing the Cu+2 ion concentration (0.5 x 10(-2) to 1.0 x 10(-2) mol dm(-3)), an increase in total conversion of monomer, grafting ratio, efficiency, and add on was observed. Grafting ratios increased with an increase in concentration of mandelic acid and reaches its maximum value at 0.8 x 10(-2) mol dm(-3) It was observed that grafting onto guar gum takes place efficiently when monomer and hydrogen ion concentrations are 20.0 x 10(-2) and 2.2 x 10(-2) mol dm(-3), respectively. Optimum temperature and time for obtaining a maximum grafting ratio and efficiency was found to be 35 +/- 0.2 degrees C and 2 h, respectively. The plausible mechanism of grafting was suggested. The graft copolymer was characterized by infrared spectroscopy and thermogravimetric analysis.