The electrochemical performances of Li4Mn5O12 powders prepared via an aqueous sol-gel method using either citric acid or L-lysine as complexing and combusting agent are compared. At current rate of 0.1 C, a discharge capacity of 163 mAh g(-1) and a good cyclability are obtained for powder cathode materials prepared with L-lysine and processed as composite electrode. Films of the corresponding Li4Mn5O12 were deposited by direct spray coating of precursors' solutions and subsequent thermal treatment at 400 degrees C. Films exhibit better electrochemical performances than powders with a discharge capacity of up to 165 mAh g(-1) at 0.1 C and a capacity retention of 95% after 100 cycles at 0.5 C and 89% after 100 cycles at 2 C. Increasing the active material loading up to 2 mg cm(-2) leads to a small loss of cyclability, especially at high cycling rates, but a specific capacity of 275 mu Ah cm(-2) is still achieved at 2 C. These values of specific capacities are higher than those observed in the literature for lithium manganese oxide films.