The present work deals with a novel sonochemical synthesis of calcium carbonate (CaCO3) by reverse miniemulsion technique using ultrasound and compares the results with conventional route of synthesis without the ultrasound. The effect of power density on the obtained particle size, crystallinity, crystallite size and morphology of the prepared CaCO3 were investigated and optimized. XRD, SEM, TEM, FTIR were used for the characterization of prepared CaCO3 particles. The results evinced that the size of the obtained calcium carbonate particles accomplished by acoustic cavitation method was about 20 nm, exhibited uniform morphology and gave a maximum of 98% conversion. It was clearly observed that conventionally synthesized CaCO3 particles had wide particle size distribution (10-150 nm) and gave lower yields than sonochemical synthesis method. This work also established that sonochemical synthesis method saves more than 80% of energy as compared to the conventional method of synthesis. Finally it is evident that ultrasonication technique could be a very efficient and faster synthesis tool in controlling particle size and morphology resulting in the overall reduction in reaction time and energy. (C) 2015 Elsevier B.V. All rights reserved.