This paper investigates the low temperature thermochemical treatments in conventional tube furnace of hybrid treating which introduce nitrogen and carbon simultaneously with the aim to improve surface properties of austenitic AISI 316L and Duplex 2205 stainless steels. The expected resulting layer is a structure termed expanded austenite which is supersaturated with nitrogen and carbon and this structure are responsible to the higher hardness and better wear properties without impairing its corrosion resistance. Characterization of this expanded austenite layers have performed including Line scan elemental analysis, SEM and SPM were used to reveal the characters of the produced thin layers. Elemental profile of nitrogen and carbon across the hybrid treated layer were obtained by line scan mode EDS-SEM. © 2011 IEEE.