Spinel Li4Ti5O12 has been considered as one of the most prospective anode materials for Li-ion microbatteries. Homogeneous and crack-free Li4Ti5O12 film with thickness around 200 nm have been deposited on Pt/Ti/SiO2/Si(100) substrate by r.f. magnetron sputtering. The influence of the post-annealing treatment on the phase composition, structure and electrochemical properties was studied. The Li/Ti molar ratio in the films decreased with an increasing oxygen fraction. The amount of Li4Ti5O12 phase increases with increasing annealing temperature from 500°C to 700°C. Electrochemical characterization of samples heat-treated at 600°C presents a redox reaction around 1.55 V indicating that the film contains Li4Ti5O12 spinel. The high capacity and good reversibility in the sample post-annealing treatment at 600 °C can be attributed to high crystallinity of Li4Ti5O12 and amorphous TiO2 phase.