Nitric acid passivation was applied on a high nitrogen austenitic stainless steel (HNS) to improve its pitting corrosion resistance which was obviously decreased by severe cold deformation. According to cyclic polarization and immersion results, the pitting corrosion resistance of HNS was found significantly improved by passivation and further enhanced with increase of the passivation temperature. In addition, severely cold-worked HNS passivated at 75 degrees C obtained much better pitting corrosion resistance, as its pit density was decreased by more than 50% compared with unpassivated solution-treated HNS. But cold-worked matrix showed a weaker passive film formation ability. Based on electrochemical results and XPS analyses, this improvement was attributed to the sharp increase of Cr oxide enrichment and the clear decrease of cation vacancy density of passive films. Besides, the dissolution of MnS inclusion had no effect on the improvement of pitting corrosion resistance. (C) 2019 The Electrochemical Society.