Nanosized CaSnO3 is synthesized by a hydrothermal process and characterized by X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). The SEM observation shows the sample has a porous flowerlike morphology. The electrochemical results exhibit that the stable and reversible capacity of 547mAhg−1 is obtained after 50 cycles at 60mAg−1 (0.1C) and the corresponding charge capacity is determined to be 316mAhg−1 at the current density of 2.5C. Cyclic voltammetry and electrochemical impedance spectroscopy data are analyzed to complement the galvanostatic results. The observed excellent performance is attributed to the porous structure and large surface area of flowerlike CaSnO3.