In this study, the i 2 /Al 2 O 3 ceramic matrix composite coating was thermally sprayed on Ti6Al4V substrate to improve its tribological behavior. So in the first step nanostructured i 2 intermetallic compound and i 2 /Al 2 O 3 nanocomposite were produced via mechanical alloying (MA). The reached powders were evaluated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), microhardness test and heat treatment. Thermodynamic analysis of these systems was carried out using semi-empirical miedema model. The obtained results were shown that i 2 intermetallic was formed in gradual mode at 60h of mechanical alloying of Nb-Si powder mixture. After the formation of this compound in the early stages of milling, the Nb 5 Si 3 intermetallic compound was also created. Finally the reaction between Nb 5 Si 3 and residual Si led to the formation of i 2 phase. The in situ i 2 /Al 2 O 3 nanocomposite was formed via mechanical alloying of Nb 2 O 5 , Al and Si powders. The reaction was completed in 40h of milling. The results of the heat treatment of powder particles at 700 °C showed that these compounds had good thermal stability. The powders produced by mechanical alloying were agglomerated in order to gain the suitable size for spraying. Finally the agglomerated powders were coated on Ti6Al4V alloy by atmospheric plasma spraying method. The characterization of coatings was performed using x-ray diffraction, scanning electron microscope, energy dispersive spectroscopy and microhardness indentation. To measure the porosity of coating, the image analyzer was used. The results showed that, in spite of growth of grain size and the decrease of internal lattice strain of nanostructured compounds, the grain size of coating after thermal spray was still in nanometer scale. The achieved coatings were uniform and had good adhesion to substrate. Also the value of hardness of nanocomposite coating was high and equal to 1100 HV. The tribological behavior of substrate and coatings was characterized by pin on disc method at room temperature. The results showed that the dominant mechanism of wear was abrasive wear. High temperature oxidation behavior was studied using thermal analysis. It showed that nanocomposite coating can be used to protect Ti6Al4V substrate at 700 °C. Keywords Ti6Al4V, Thermal spraying, Nanocomposite, Thermodynamic investigation, i 2 , Al 2 O 3 .