The measurement of theological properties of electrodeposited NiOOH films simultaneous to cyclic voltammetry using an electrochemical quartz crystal microbalance and fast quartz crystal impedance at 10 MHz for thin and thick films are reported. The resulting impedance parameters are analyzed using the model proposed by Martin and Granstaff for multiple viscoelastic layers on a piezoelectric resonator. Nickel battery oxide films show an inversion in mass-to-charge relation as shown previously by Scherson and Hillman in the first reduction-oxidation cycles but without appreciable change in their viscoelastic behavior. Changes in the motional resistance are not recovered in the first cycle during "break in." After hundreds of cycles, NiOOH films undertake an important viscoelastic change, and the aged films become softer. The oxidized state shows always higher sheer modulus than the reduced state.