Lithium manganese oxide (Li2-xMnO3-y) thin films have been deposited from activated Li2MnO3 powder by radio frequency magnetron sputtering for the first time in the literature and subjected to electrochemical characterization. Physicochemical characterization by X-ray diffraction has revealed the formation of the thin films with crystallographic phase identical to that of the powder target made of Li2-xMnO3-y. The Li:Mn atomic ratio for the powder and film are calculated by X-ray photoelectron spectroscopy and it is found to be 1.6:1.0. From galvanostatic charge discharge studies, a specific discharge capacity of 139 μAh μm−1 cm−2 was obtained when cycled between 2.00 and 3.50 V vs Li / Li+. Additionally the rate capability of the thin film electrodes was studied by subjecting the cells to charge-discharge cycling at different current densities in the range from 10 μA cm−2 to 100 μA cm−2.