Generally, upgradation of the petroleum residue to valuable product is done through the catalytic and thermal cracking using very high temperature and pressure. The ultrasound assisted cavitation is the novel technique to intensify the cracking of asphaltene present in the vacuum residual feedstock. The up-gradation of residue was carried out with application of low frequency (24 kHz), high intensity ultrasound under atmospheric pressure and ambient temperature in a batch reactor. In the present work, vacuum residue, having high viscosity was subjected to acoustic cavitation for different reaction times (15 min to 90 min) and with different probe diameters at ambient temperature and pressure. The effect of ultrasound on the upgradation of residue (asphaltene degradation) has been studied with surfactant as emulsifier as well as without surfactant. Also, the effect of acoustic cavitation has been studied on the physico-chemical properties of residue. The study revealed that the asphaltene content of the vacuum residue decreased from 13.5 (initial asphaltene present in residue) to 7% (wt.%). It has been also observed that the physico-chemical properties of residue reduced with the influence of ultrasound energy. (C) 2011 Elsevier B.V. All rights reserved.