The electrochemical responses of amorphous thin films of lithium doped tungsten trioxide (LixWO3) prepared by the sol-gel method were studied. The electrode mass change in the oxide films during cyclic voltammetry and chronoamperometry measurements was evaluated with electrochemical quartz crystal microbalance (EQCM). The electrode mass change and electrochemical performances depend on the lithium doping level. Higher lithium doping levels lead to better electrochemical performances and to higher electrode mass changes in the insertion- deinsertion process. The electrochromic properties of the films investigated in situ using a spectroelectrochemical method are in agreement with EQCM measurements. The bleaching process in the lithium doped film was complete whereas in pure WO3 films a residual coloration was observed.