This paper deals with modelling of homogeneous reactions enhancement by ultrasound. First a survey of bubble dynamics is proposed, then a convenient model is carried out assuming pressure uniformity, but including heat and mass transfer (interdiffusion of gas and vapour inside the bubble and vapour-liquid phase change at the interface). The numerical solution consists in an orthogonal collocation using Chebychev polynomials for spatial integration together with a Gear method for time integration. At the end of a collapse, all the reactions of dissociation yielding free radicals in the bubble are assumed at thermodynamic equilibrium so that a local minimization of Gibbs free energy provides the local composition in the bubble. Influence of physico-chemical properties of gas and liquid as well as experimental conditions on maximum temperature and free radicals concentration have been then derived.