Urea-assisted auto-combustion synthesis was used for the easy and scalable preparation of TiO2 nanoparticles for use as anodes in lithium-ion batteries. The prepared TiO2 powder was annealed at 300°C, 400°C, 500°C and 600°C to optimize the system and assess the effects of particle size on electrochemical properties. X-ray diffraction patterns confirmed that pure anatase phase TiO2 formed at up to 500°C, above which mixed phases of anatase and rutile emerged. Field-emission transmission electron microscopy showed that spherical particles of 8–25nm were formed. The electrochemical performances of annealed TiO2 samples were tested by charging/discharging, C-rate measurement and electrochemical impedance spectroscopy. It was clearly found that the crystal particle size has a striking impact on the Li insertion behavior and lithium storage capability. TiO2 nanoparticles electrode annealed at lower temperature 300°C showed high rate capability, excellent capacity retention and high electrical conductivity due to its very small particles and nonideal crystal lattices.