Ultrasonic degradation of low-density polyethylene (LDPE) polymer in o-dichlorobenzene as a solvent has been investigated using viscometry as a technique for monitoring the rate of degradation. Different concentrations (1%, 1.2%, and 1.4%, w/v) and different volumes (50 ml, 75 ml and 100 ml) were subjected to ultrasonic irradiation at two different operating temperatures (60 degrees C and 80 degrees C) to study the effect of different operating parameters on the extent of degradation. It was found that extent of degradation increases with a decrease in reaction volume and concentration. Also lower operating temperature plays major part in enhancing the cavitational effect and hence results in higher extent of degradation. The difference in the values of limiting viscosities (constant solution viscosity which does not decrease by further ultrasonic irradiation) for 50 ml and 75 ml solutions for each of 1% and 1.2% concentration was negligible. But 1.4% solution at 100ml volume showed slightly higher value of limiting viscosity than that for 50 ml and 75 ml indicating lower efficacy of ultrasonic degradation at higher concentrations and volume of operation. (C) 2008 Elsevier B.V. All rights reserved.