The role of molybdenum in the interaction of the composed phases of 2205 duplex stainless steel (DSS) in the 3.5-wt% NaCl solution was investigated, by comparing the untreated 2205 DSS sample with two single-austenite and single-ferrite samples prepared via selective dissolution. The results demonstrate that, the interaction is beneficial to the whole passive film properties of 2205 DSS by promoting both the gamma-phase and alpha-phase. The passivity of 2205 DSS at high potential strongly depends on the protective ability of Mo species. Compared with alpha-phase and gamma-phase, Mo species of the 2205 DSS are more capable of keeping stable and being beneficial to passive film recovery, which make 2205 DSS show enhanced performance in pitting resistance and repassivation. (C) 2018 Elsevier Ltd. All rights reserved.