AbstractAn investigation was carried out to assess the corrosion resistance of duplex stainless steel that was surface alloyed with ruthenium. It was found that vapour deposited ruthenium on the surface of a duplex stainless steel improved the corrosion resistance, especially if the alloy is annealed after surface deposition has been carried out. The ruthenium apparently increases the corrosion potential to more noble values, and also inhibits anodic dissolution. This method promised a more economical technique of cathodic modification than bulk alloying.