Spherical porous tin oxide was fabricated via a spray pyrolysis technique. TEM revealed that the primary SnO2 crystals had an average size of about 5nm. The electrochemical measurements showed that the spherical porous SnO2 samples have excellent cyclability, which can deliver a reversible capacity of 410mAhg−1 up to 50 cycles as a negative electrode for lithium batteries. The second step of the study was to thermal treat the initial tin oxide for 3h at 600, 800, 1000 and 1200°C, respectively, in order to identify the particle size effect on the electrochemical performance toward lithium. It was found that the morphologies of these spherical clusters could be maintained even after thermal treatment at 1200°C. It was also proved that finer the size of the tin oxide particles the better the electrochemical performance.