BaTiO 3 nanopowders were attempted to synthesize by using a novel straight-forward, solvent free reactions under autogenic pressure at elevated temperature (RAPET) approach. The as-prepared BaTiO 3 nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, high-resolution TEM, and convergent-beam electron diffraction. It was found that Ba(OH) 2 ·8H 2 O and Ti(OBu) 4 could be appropriate starting materials to synthesize BaTiO 3 at 973K for 2h by using RAPET approach. Pure tetragonal BaTiO 3 nanopowders could be obtained by exceeding moderate amount of Ba(OH) 2 ·8H 2 O in the starting materials. The obtained BaTiO 3 nanoparticles had well dispersion and crystallinity, possessed a tetragonal perovskite structure at room temperature and relatively narrow particle size distribution.