Our previous presentation showed the influence of different factors on the kinetic rates of the sonodegradation of an azo-dye. Blue mordant 9 has been used as the model substrate. Results obtained when an aqueous solution of blue mordant 9 was sonicated in the presence or not of UV light are reported in this paper. Several factors, such as reaction time, temperature and presence of an additive have been varied and their influence on the sonodegradation rate has been monitored.