Thermal oxidative degradation kinetics of a nanocomposite alkyd-melamine formaldehyde resin containing surface-modified silica were investigated by thermogravimetric analysis. For this goal, the surface of the silica nanoparticles was modified with glycidoxypropyl trimethoxysilane. Afterwards, a nanocomposite alkyd-melamine formaldehyde resin containing 3% (wt.) ratio of surface modified silica was prepared by an in situ polymerization method. The degradation kinetics of this resin were investigated using different methods. The activation energies of different mechanism models were determined by the Coats-Redfern method. It was concluded that the actual reaction mechanism obeyed three-dimensional diffusion compared with the values obtained from the Kissinger and Flynn-Wall-Ozawa methods.