Abstract: A method for the dynamic measurement of the progress of a chemical reaction at an electrochemical interface. The method comprises: applying a direct coherent light to a solid interface within a sample in which the chemical reaction is occurring; measuring a scattering of the light after it contacts the electrode; and autocorrelating the scattering information with previously obtained scattering information for the electrode. This method allows the measurement of the progress of the chemical reaction to be made in situ, without removing the solid interface from the sample or stopping the chemical reaction. The coherent light source is, for example, a laser such as a low power helium-neon laser and a solid state laser. The chemical reaction measured can be, for example, metal finishing, electrochemical machining, corrosion protection, metal deposition, electrochemical production, waste water treatment or electrowining.