Mo surface-modified layer in Ti6Al4V alloy was prepared using plasma surface alloying technique. Microstructure of the modified layer was analyzed using X-ray photoelectron spectroscopy (XPS), rough-meter and GDA750 glow discharge optical emission spectrometer. Phase composition of the Mo surface-modified layer was characterized by D/max 2500 X-ray diffraction. Results show that the Mo surface-modified layers consist of pure Mo surface layer with < 1 1 0 > and < 2 1 1 > orientations and diffusion layer. Mo 3d, O 1s, C 1s and Ti 2p, O 1s, C 1s XPS spectra are recorded at topsurface in the Mo-modified layer and titanium substrate respectively. Because of the different roughness and microstructure, the Mo surface-modified layer can to some extent inhibit bacteria adherence. (c) 2008 Elsevier B. V. All rights reserved.