Ba0.5Sr0.5TiO3 narroparticles were successfully prepared by calcined stearic acid gel in air. The as-prepared nanoparticles were characterized by X ray diffraction, transmission electron microscope, Fourier transform infrared spectrometry, UV/vis diffuse reflectance spectra and thermal gravimetric analysis, respectively. The results show that the calcined process of stearic acid get consists of a series of oxidation and combustion reactions in air. The formation of Ba0.5Sr0.5TiO3 phase starts at around 500 C and continues up to 700 C in our current experiments. BaCO3 can coexist with Ba0.5Sr0.5TiO3 phase at low calcination temperature, and then decreases quickly with increasing the calcination temperature. TEM images of Ba0.5Sr0.5TiO3 nanoparticles prepared at 600 C show that the size of most Ba0.5Sr0.5TiO3 nanoparticles is around 50-80 nm. The nanoparticles are almost ellipse in shape and link together to form necks among nanoparticles. (C) 2008 Elsevier B.V. All rights reserved.