Porous　nanocrystalline　Ti(C(0.7)N(0.3))　film　on　Ti6Al4V　substrate　was　prepared　by　plasma　electrolytic　carbonitriding　(PECN).　The　film　was　characterized　and　analyzed　by　using　a　variety　of　analytical　techniques,　such　as　XRD,　SEM,　EDX,　TEM,　FESEM,　Rockwell　C　indenter,　scratch　tester,　Vickers　microhardness　tester　and　ring-on-block　tribometer.　The　results　showed　that　the　film　was　about　15　mu　m　thick　and　its　hardness　was　Hv　2369　at　a　load　of　0.2　N.　The　adhesion　of　the　film　was　characterized　by　Lc　and　Pc　value,　and　was　found　to　be　about　42　N　and　more　than　800　N,　respectively.　The　friction　coefficients　and　wear　volume　loss　of　the　PECN-treated　samples　sliding　against　a　steel　counterpart　were　much　less　than　those　of　the　untreated　Ti6Al4V.　The　film　possessed　a　good　wear-resistance　and　antifriction　under　oil-lubricated　condition　due　to　its　high　hardness,　adhesion　and　fracture　toughness.　Also,　the　porous　surface　morphology　of　the　Ti(C(0.7)N(0.3))　film　contributed　to　the　enhanced　tribological　resistance　by　promoting　the　formation　of　lubricant　film　and　entrapping　wear　debris.　(c)　2008　Elsevier　B.V.　All　rights　reserved.