The influence of NaNO3 salt deposits on the atmospheric corrosion of zinc in humid air has been studied. Comparisons are made with the effects of NaCl and Na2SO4. Also the combined effect of NaNO3 with NaCl or Na2SO4 was investigated. The salts were applied to zinc samples prior to exposure. The samples were exposed to purified humid air with careful control of relative humidity (95%), temperature (22.0degreesC), and flow conditions. The CO2 concentration was 350 ppm and the exposure time was 4 weeks. Mass gain and metal loss results are reported. The corrosion products were analyzed by gravimetry, ion chromatography, and X-ray diffraction. Results show that the corrosion rate in the presence of NaNO3 is only a third of that registered in the presence of NaCl and Na2SO4. Further, a slight inhibitive effect of NaNO3 was found in the presence of NaCl or Na2SO4. The decreased corrosion rate in the presence of NaNO3 was attributed to the reduction of nitrate to nitrite at the zinc surface. Nitrite is suggested to act as a corrosion inhibitor toward zinc. (C) 2003 The Electrochemical Society.