AbstractA recent paper by Heeley&Little5is examined in the light of some experiments on the corrosion resistance of some Ti‐stabilised 18Cr‐8Ni steels in hot 30% nitric acid. It is inferred that the corrosion rate after prior sensitisation at 650° is determined by the thickness of a layer of exfoliated material dissolving at its outer surface as fast as it is formed and that equilibrium is not reached until the third week of test. The relevance of different types of laboratory tests to plant conditions is discu