The objective of this study is to synthesize and characterize new organic/inorganic hybrid materials obtained by grafting methacrylic polymer through the surface of metal oxide nanoparticles. Commercially available titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles were used as raw materials. For a better understanding of parameters which influence the grafting efficiency of polymers, ZnO nanoparticles were synthesized using the precipitation method. The synthetic pathway was optimized to obtain nanoparticles with high surface area and surface hydroxylation. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to determine the crystal structure, the size and morphology of nanoparticles. A polymerizable silane coupling agent, i.e. 3-(trimethoxysilyl)propylmethacrylate (MPS) was used to modify the surface of nanoparticules to obtain hydrophobic surface containing a polymerizable function. Fourier transform infrared (FTIR), solid-state (13C and 29Si) Nuclear Magnetic Resonance (NMR) spectroscopic investigations demonstrated that the silane coupling agent was fully hydrolyzed and linked to the hydroxyl groups already present on the particle surface through covalent and hydrogen bonds. Thermogravimetric data were helpful to quantify the amount of MPS linked to the nanoparticles surface. New poly(methacrylic ester)/ZnO and TiO2 nano-hybrid particles were prepared by in situ RAFT polymerization were prepared using the "grafting through" method. (Meth)acrylic homopolymers and diblock copolymers containing unconventional trialkylsilyl methacrylate (MASi) and methyl methacrylate (MMA) monomer units were grafted through the surface of nanosized particles modified by MPS. Results from FTIR and TGA analyses demonstrated that polymer chains were anchored on the nanoparticles surface. The thermal and thermo-oxidative degradation of methacrylic polymers and hybrid nanoparticles were also investigated by TGA. The effect of the RAFT polymerization on the thermal degradation of polymers was demonstrated. In addition, their apparent activation energy of degradation (Ea) was determined for the first time.