In this work firstly magnesium hydroxide (Mg(OH)2) and aluminum hydroxide (Al(OH)3) were prepared using sono-chemical reaction at solvent of water without applying any surface active agent. Effect of various sono-chemistry parameters such as power, cycles, time and volume on the size and shape of nanostructures were investigated. Secondly nanoparticles were modified and coated by ethyl cellulose capping agent. Modified nanoparticles were added to cellulose acetate and surface of wood for investigation of flame retardancy. Thermal stability were characterized by thermal gravimetric analysis (TGA). Flame retardancy were examined by UL-94 and heat release tests.