In this study, mononuclear octahedral cobalt(III) Schiff base complex [CoL3], L = (5-bromo-2-hydroxybenzyl-2-furylmethyl)imine, was synthesized from the reaction of Co(NO3)2•6H2O and the Schiff base ligand L in methanol as solvent. It used as a new precursor to prepare spinel type cobalt oxide nanoparticles by a facile solid-state thermal decomposition. Controlling the temperature and time, Co3O4 nanoparticles were obtained in air at 550ºC within 3.5 h. The Co3O4 nanoparticles was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These results confirm that the resulting cobalt oxide products were pure single-phases. Using the present method, Co3O4 nanoparticles can be produced without using any expensive organic solvent and complicated equipment. TEM result showed the products are almost flat with the size of about 10-50 nm. It has potential to be applied as a general method for preparation of other transition metal oxide nanoparticles.