Abstract Auger electron spectroscopy has been employed to study free surface segregation in a 3.5Ni-Cr-Mo-V steel of varying manganese content. The study was designed to complement an earlier investigation of grain boundary segregation in the same materials. In situ heating at 450 °C initially produced a substantial amount of sulphur segregation but only minimal phosphorus segregation to the free surface; in the grain boundary case, however, phosphorus was the principal segregant, and sulphur segregation was not detected. Examination of surfaces which had been heated-sputtered-heated revealed examples of site competition, particularly between sulphur and phosphorus. Alloying element interactions were also observed; for instance, materials with a high manganese content were found also to exhibit a higher surface nickel content, consistent with the previous grain boundary observations.