In this article, nano-Bi2O3 powder was synthesized by the solution combustion synthesis method using bismuth nitrate as oxidant and citric acid as fuel. The investigation was focused on the effect of calcination temperature on the size of nano-Bi2O3, phase transformation, and morphology. The -Bi2O3 powder was synthesized at 300 degrees C for 2h and characterized by SEM, TEM, XRD, and TG-DTA. Bi2O3 nanoparticles as small as 10.7nm were formed using 0.005mol citric acid as the fuels and 0.04g PEG-20000 as the dispersant.