A nickel oxide (NiO) precursor was prepared using Pechini method. The NiO nanoparticles were prepared by calcination of NiO precursor at temperatures ranging from 300 to 700 A degrees C. The resulting NiO nanoparticles were characterized by X-ray photoelectron spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy. To hamper NiO nanoparticles aggregation, the NiO nanoparticles surface was treated using (3-mercaptopropyl)-trimethoxysilane as a coupling agent. Next, nanocomposites of poly(methyl methacrylate) and modified NiO nanoparticles were successfully prepared by in situ bulk polymerization with 2,2'-azobis(isobutylonitrile) as initiator. The obtained nanocomposites were characterized by XRD and thermogravimetric analysis.