In this letter, we report the first facile open-bench synthesis of BaTiO3, SrTiO3 nanocrystals, and their nanosolid solutions BaxSr1-xTiO3 (BST) at 80 degrees C. The size of the BST nanoparticles was readily tuned from similar to 50 to similar to 10 nm with achievable giant dielectric constants. The process yielded these important perovskite mixed-metal oxide crystals of high quality on the nanometer scale without a history of thermal stress. This new synthesis system involves inorganic starting materials without organic components and does not require demanding conditions such as an inert environment, high pressure, and high temperature.