The synthesis of BaSnO3powders has been investigated at lyothermal conditions (temperature of 250 °C; t = 6 h), starting from SnO2·xH2O and Ba(OH)2and methanol, ethanol, isopropanol and acetone as solvents. Among them isopropanol was found to be the most suitable medium for preparing BaSnO3. By addition of the modifier Genapol X-080 during the processing, the BET specific surface area of the end-powder was increased by a factor of 10. The as-prepared powder consisted of BaSn(OH)6. The thermal behavior, the crystallization behavior and the structure evolution of the powder during heating treatment have been studied with the TG-DTA-MS, XRD and FTIR. The weight loss of the as-prepared powder of about 12 wt% heated up to 1200 °C is mainly attributed to the dehydration around 260 °C which leads to the structure rearrangement and the building of the [SnO6] octahedra. At this temperature BaSn(OH)6converts to an amorphous phase, from which BaSnO3nucleates and grows with increasing temperature. The obtained BaSnO3powders had a BET specific surface area of 16.56 m2/g and a primary crystallite size of 49 nm.