The chemical dissolution of anodically grown Si oxides in acidic fluoride medium has been studied in-situ with the Bending Beam Method (BBM). Current and deflection transients were recorded after switching the electrode from the given polarization conditions to zero applied field and monitoring the etchback process. Oxide stress values estimated with this approach are free from contributions due to film electrostriction and to changes in surface tension. Transients recorded after polarization in the regime of current or potential oscillations show dissolution patterns which contain information on the properties of oxide film along its depth profile.