A method of manufacturing crystalline titanium dioxide (TiO2) powder, a method of a negative active material, and a negative active material and a rechargeable lithium battery including the crystalline titanium dioxide (TiO2) powder are provided. The method of manufacturing the crystalline titanium dioxide powder may include: preparing a titanyl chloride (TiOCl2) aqueous solution by adding titanium tetrachloride (TiCl4) to water at a temperature ranging from 0° C. to 10° C.; adding alcohol, urea, and a sphere-shaping agent to the titanyl chloride aqueous solution to prepare a mixture; and hydrothermally synthesizing the mixture under a pressure ranging from 1.5 atm to 5 atm at a temperature ranging from 80° C. to 155° C.