Nanosized zirconium oxide (ZrO2) powders were synthesized by the microwave combustion synthesis (MCS) using glycine as the fuel without using any template, catalyst or surfactant. For the purpose of comparison, it was also prepared using solution combustion synthesis (SCS). The assynthesized ZrO 2 was characterized by X-ray powder diffraction (XRD), Fourier Transform infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of cubic phase ZrO2. FT-IR was used to investigate the adsorption of water and CO2 on ZrO2 surface and confirm the formation of Zr-O phase. The formation of ZrO2 nanospheres was confirmed by HR-SEM and TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively. Copyright © 2013 American Scientific Publishers.