The compound system, Mn1-xMo2xV2(1-x)O6 (0 less than or equal to x less than or equal to 0.4), synthesized by solid state reaction forms the brannerite structure. The electrochemical reaction mechanism as the anode for Li secondary batteries was investigated. X-ray diffraction (XRD) analysis clearly indicated that Mn0.6Mo0.8V1.2O6 anode irreversibly transformed from crystalline brannerite to amorphous phase via a rock-salt type structure during the first lithium insertion/removal reaction. The charge compensation and the change in the local environmental structure during the Li insertion/removal were confirmed by X-ray absorption fine structure (XAFS) of manganese, vanadium and molybdenum.