Accelerated electrochemical tests with cyclic immersions and emersions and electrode potential measurements during the periods of immersion help to assess the corrosion behavior of metallic material under different climatic conditions and to understand the atmospheric corrosion or passivation mechanism. Results of both natural exposure tests and laboratory tests may often be expressed by the linear bilogarithmic law log p = A + B log t, where A measures the initial corrosion intensity and B measures the passivating action of the atmosphere. Correlations between electrode potential measurements and the values of Parameters A and B are discussed.