Lithium silicate thin films were successfully deposited by pulsed laser deposition (PLD) technique using an ArF excimer laser. The ionic conductivities, the structures and the stability against CO 2 of the lithium silicate films were examined. The ionic conductivity value at 25 °C was 2.5×10 -8 S cm -1 for Li 2 SiO 3 film and 4.1 ×10 -7 S cm -1 for Li 4 SiO 4 film. Li 4 SiO 4 film was found unstable to CO 2 to form Li 2 CO 3 , but Li 2 SiO 3 film was stable. Solid-state thin film batteries (TFB) consisting of an amorphous lithium silicate electrolyte, crystalline LiCoO 2 positive electrode and Li metal negative electrode were fabricated and characterized. The batteries performed good stabilities for cycles. Higher apparent capacity was obtained in the TFB using Li 4 SiO 4 electrolyte than Li 2 SiO 3 , which is due to the higher conductivity of the Li 4 SiO 4 film.