To realize a suitable supercapacitor nanomaterial, the recently developed technique of reaction under autogenic pressure at elevated temperature has been employed by us to synthesize SnO2 hexagonal nanocrystals and SnO 2 @ C nanocomposites. The synthesis at different temperatures (viz. 500, 600, and 700°C) yields three different composites. Characterization of these composites by various methods confirms the structural (XRD, Raman, FT-IR) and nanoparticulate (TEM, HRTEM) nature of the synthesized materials. TEM studies including HRTEM reveal that all the synthesized SnO2 and SnO2@C nanomaterials are highly crystalline with hexagonal shape. Cyclic voltammetric studies carried out to examine the capacitance of SnO 2@C in 1 M H2SO4 show that the nanocomposite prepared at 700°C has a maximum specific capacitance of 37.8 F/g at a scan rate of 5 mV/s.