The results presented on simultaneous oscillations of the potential and deflection of a platinum cantilever electrode during the galvanostatic oxidation of formic acid in acid media are the first experimental evidence that the oscillation arising in the course of galvanostatic oxidation of simple organic compounds is associated with the change of surface stress of the electrode. The results of the bending beam experiments may open up new vistas in the quantitative description of the surface energetics of heterogeneous oscillation phenomena.