This paper reports results of an investigation aiming at finding what affects the microstructure and density of barium titanate (BaTiO3) by spark-plasma-sintering (SPS) process. Nano-sized BaTiO3 powders were prepared by different chemical methods and then sintered under different SPS conditions such as synthesis methods, heating rate, holding time and sintering temperature, etc. The possible effects of these factors upon the densities and grain size have been analyzed in details. The results show that dense BaTiO3 with grain size of less than 100 nm can be obtained by controlling the conditions during SPS process. (C) 2003 Elsevier Science B.V. All rights reserved.