Mg(OH)(2) nanoparticles were synthesized by a rapid microwave reaction. The effect of sodium dodecyl sulfonate (SDS as anionic surfactant) and cetyl tri-methyl ammonium bromide (CTAB as cationic surfactant) on the morphology of magnesium hydroxide nanostructures was investigated. Multi wall carbon nano tubes was organo-modified for better dispersion in cellulose acetate matrix. The influence of Mg(OH)(2) nanoparticles and modified multi wall carbon nano tubes (MWCNT) on the thermal stability of the cellulose acetate (CA) matrix was studied using thermo-gravimetric analysis (TGA). Nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Thermal decomposition of the nanocomposites shift towards higher temperature in the presence of Mg(OH)(2) nanostructures. The enhancement of thermal stability of nanocomposites is due to the endothermic decomposition of Mg(OH)(2) and release of water which dilutes combustible gases. 2015 JNS All rights reserved.