A thin film of Si was vacuum-deposited onto a 30μm thick Ni foil from a source of n-type of Si, the film thickness examined being 200–1500Å. Li insertion/extraction evaluation was performed mainly with cyclic voltammetry (CV) and constant current charge/discharge cycling in propylene carbonate (PC) containing 1M LiClO4 at ambient temperature. The cycleability and the Li accommodation capacity were found to depend on the film thickness. Thinner films gave larger accommodation capacity. A 500Å thick Si film gave a charge capacity over 3500mAhg−1 being maintained during 200 cycles under 2C charge/discharge rate, while a 1500Å film revealed around 2200mAhg−1 during 200 cycles under 1C rate. The initial charge loss could not be ignored but it could be reduced by controlling the deposition conditions.