The paper describes modification of colloid silica nanoparticles, using 3-(triethoxysilyl)propylsuccinic anhydride (TESPSA) as a reagent. Anhydride groups were grafted to the silica surface by an interaction of the surface silanol Si-OH groups with reactive ethoxy groups of TESPSA. Elemental analysis, FTIR and H-1 NMR spectroscopy were employed to characterize silica nanoparticles before and after surface modification. It was demonstrated that only fifty percent of silica surface silanol groups are involved in the reaction with TESPSA. Size distribution of nanoparticles determined by atomic force microscopy (AFM) technique shows that nanoparticles preserve their size upon modification. TESPSA-modified silica nanoparticles can be used as polyfunctional curing agent for epoxy resin. (C) 2011 Elsevier B.V. All rights reserved.