Cold rolled plain steel sheets were heat treated in a reducing atmosphere of N 2 and H 2. The aim of the work was to simulate the heat treatment used in a continuous galvanizing line and to analyse by ESCA the surface state of the sheet just before it is dipped into the zinc bath. The heat treatments were performed in a furnace incorporated in the ESCA system. This made it possible to analyse surface uninfluenced by air exposure. The gas atmosphere was 15 v/o (volume percentage) H 2, 85 v/o N 2 at 0.1 M Pa. The dew point of the gas was varied between -20°C and -30°C. The samples were heated to 850°C and step-cooled to 450°C within 2 min and then cooled to room temperature. The compositions of the alloys were systematically varied with respect to the elements Mn, Si, Al, V, Ti and Nb. The heat treatment leads to a complete reduction of the air-formed iron oxide. The H 2O-content of the gas was too high to preclude oxidation of the stronger oxide-forming elements Mn, Si, Al, V and Ti. The oxides are distributed along the grain boundaries and as islands on the surface. By ion etching the thickness of the islands was estimated to be about 50 nm. The oxide contains the alloying elements Mn, V, Si, Al and Ti. Niobium could not be detected in the oxide. The heat treatment also caused segregation of the impurities S, Sb and Sn to the free surface. These elements are easily removed by light etching, which implies that they are merely adsorbed on the surface.