The reactions of an epoxy prepolymer based on bisphenol A diglycidylether (DGEBA) with γ-aminopropyltriethoxysilane (γ-APS) are studied. The results of different techniques are compared: size exclusion chromatography, differential scanning calorimetry, chemical titration, and Fourier Transform Infrared absorption. Epoxy amine reactions are shown to be faster than the crosslinking reactions between alkoxysilane and hydroxy groups, and thus, can be studied seprately. The reactivity of the epoxy group in DGEBA is compared with that of phenylglycidylether (PGE). And the reactivity of the amine group of γ-APS is compared with that of hexylamine. The kinetic constants are calculated with a mechanism which takes into account both the catalytic and noncatalytic reactions. The ratio r = k2/k1 of the reactivity of the secondary to the primary amino-hydrogens was also determined. The values of r are 1.4 for hexylamine and 1.2 for γ-APS. The reactivity of the epoxy groups are the same for both PGE and DGEBA.