A high-rate, continuous synthesis of functional nanomaterials using a home engineered reactor is reported. The reactor is able to produce low-cost, kilogram-scale BaTiO3 nanopowders with a nanocrystalline particle size less than 30 nm at mild temperatures (<100 °C) and ambient pressure. Nebulization and collision of warm microdroplets (60–80 °C) of Ba(OH)2 and Ti(O-nBu)4 very quickly result in total hydrolysis and subsequent conversion to BaTiO3, yielding 1.3 kg/day of high purity, highly crystalline nanoparticles (25–30 nm). This synthesis procedure also enables high-rate production of TiO2 anatase (2.9 kg/day). It therefore provides a general platform for processing and scaling up of functional inorganic nanomaterials under very mild conditions.