Ir-Zr gradient coating was obtained on the Mo substrate by double glow plasma. The structure and composition of the coatings were confirmed by SEM, AFM, XRD and EDS, respectively. The adhesion strength between the coating and the substrate was evaluated by a scratch tester. Compared with preferential growth orientation of (2 2 0) crystal plane of Ir coating, the Ir-Zr coating had a random orientation structure. The RMS roughness value of the Ir-Zr coating is 19.3 nm, which was lower than the roughness value of 45 nm for Ir coating. The Ir-Zr coating with the thickness of 5.0 mu m was composed of two distinct layers. The proportion of Ir decreased gradually from the surface of the coating to the coating/substrate interface. The Zr distribution decreased slightly in the coating. The adhesive force of the Ir-Zr coating was 15 N. (C) 2012 Elsevier B. V. All rights reserved.