High temperature gas nitriding of stainless steels allows obtaining austenitic or martensitic cases with good wear and corrosion resistance. The texture evolution during high temperature nitriding of a ferritic-austenitic duplex stainless steel is studied. The microtextures were determined by Electron Back Scattering Diffraction (EBSD) analysis. UNS S31803 duplex stainless steel was gas nitrided under a 0.065 MPa N(2) partial pressure at 1423 K for times between 2.7 and 28.8 ks. At the initial stages of the nitriding treatment austenitic cases were formed, with austenite sideplates growing towards the ferritic-austenitic core, holding a Kurdjumov-Sachs (K-S) type orientation relationship with prior existing ferrite grains. The corresponding austenite texture at the steel surface is {011} <411>. For longer nitriding (28.8 ks) times the microstructure coarsens, ferrite is consumed and austenite grain growth occurs, resulting in grains 150-200 mum in diameter and a {011}<211> texture, typical of austenite in hot rolled or solution treated duplex stainless steels. The texture intensities decrease with increasing nitriding time. These results are discussed taking in account nitrogen gradients and nitrogen supersaturation built up during the nitfiding treatment.