Synthesis temperature and purity of perovskite materials are key challenges facing the scientific community. This work aims to address these challenges by developing an innovative low temperature synthesis pathway for preparation of carbonate-free perovskite nanocrystals. The method is based on an ultrasound-assisted wet chemical processing method. Nanocrystals are characterized and observed by X-ray diffraction (XRD), field-emission scanning electron microscopy and high-resolution transmission electron microscopy techniques. XRD studies show that very fine BaTiO3 nanocrystals (<11 nm) free from any by-products such as BaTi2O5 and BaCO3 are synthesized at 50 degrees C. Moreover, the method developed here can be used as a strategy for synthesizing carbonate-free perovskite nanocrystals. We believe that the method developed in this work provides a simple, cost-effective, and convenient route for synthesizing a variety of perovskite materials for assembling in nanotechnology.