Thin films of LiMn20~ spinel were fabricated by RF magnetron sputtering. The as-deposited films were amorphous but could be crystallized into a spinel structure by rapid thermal annealing in an oxygen atmosphere. The electrochemical performance of 2000 A thick LiMn2Q thin-film cathodes were tested in a LiMn204/IM LiCIQ in PC + DME/Li cell. LiMnzO4 spinel films prepared at 750~ showed good intercalation kinetics and very promising cycling behavior. Room temperature 2 2 cycling of these films had capacities of about 50 FtAh/cm .~tm at 200 FtA/cm and maintained more than 98% of their original capacity after more than i000 cycles.