The present work involves hydrogen intercalation into and deintercalation from amorphous WO3 film prepared by radio frequency (rf) magnetron sputtering method in 0.1 M H2SO4 solution by means of cyclic electrogravimetric curve obtained simultaneously with cyclic voltammogram. The results obtained from EQCM measurement were satisfactorily analysed to validate the results obtained from successive cyclic voltammetry. The irreversible mass change, based upon irreversible trap sites produced and internal stresses developed during the sputter deposition of the hydrated WO3 film, is extremely reduced with cycling and by dehydration at the early cycles. Water absorbed chemically into the dehydrated film promotes the hydrogen intercalation into and deintercalation from the film on the one hand and the degradation of the film on the other hand.