Maghemite (gamma-Fe2O3) nanopowder was prepared by the thermal decomposition of Fe-urea complex ([Fe(CON2H4)(6)](NO3)(3)) that was synthesized by various routes including wet and dry synthetic methods. Then the effects of synthetic routes of the [Fe(CON2H4)(6)](NO3)(3) on resulting iron oxide crystalline phases and their magnetic properties have been studied using X-ray powder diffraction (XRD) and magnetic measurements. The result of XRD shows that the iron oxide crystalline phases are strongly dependent on the synthetic routes of the [Fe(CON2H4)(6)](NO3)(3). When [Fe(CON2H4)(6)](NO3)(3) is synthesized in ethanol, thermal decomposition of the compound results in pure gamma-Fe2O3. When [Fe(CON2H4)(6)](NO3)(3) is synthesized either by an aqueous synthetic method or by a dry synthetic method, however, thermal decomposition of the compound results in mixed phases of gamma-Fe2O3 and alpha-Fe2O3. Magnetic measurements show that resulting iron oxide nanopowder exhibits a ferromagnetic characteristic with a maximum saturation magnetization (Ms) of 69.0 emu/g for the pure gamma-Fe2O3 nanopowder. (C) 2009 Elsevier B.V. All rights reserved.