Polymaleimide/Silica nanocomposites were synthesized from N-gamma-Triethoxysilylpropyl- maleamic acid (TESPMA) through sol-gel process, imidation reaction of the maleamic acid functional groups and thermal polymerization of the formed maleimide at elevated temperature. These nanocomposite materials were characterized by Fourier transform infrared analysis (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM). It was found that the inorganic networks chemically bound to polymaleimides enhanced the thermal stability of these nanocomposites greatly. Nevertheless, incorporation of colloidal silica did not make positive contributions to the thermal stability, although the weight fraction of the inorganic part in the composite was increased significantly.