The objective of the work was to investigate temperature impact on corrosion of air-preheater tubes of oil shale CFB boilers. With this objective in view, laboratory corrosion tests of carbon steel St 33 used for manufacturing of air-preheater tubes have been carried out in the atmosphere of air and water steam in the presence of oil shale ash in the temperature range of 75-110 degrees C. The results have shown that corrosion rate of the metal was maximal at the temperature of 90 degrees C and minimal at the temperature of 110 degrees C which could be recommended as the operation temperature of the metal of air-preheater tubes of oil shale CFB boilers with respect to safe operation of tubes.