The present study was carried out to synthesize NbAl 3 /Al 2 O 3 intermetallic matrix nanocomposite by mechanical alloying (MA) using Nb 2 O 5 and Al as raw materials. This nanocomposite was produced through a mechanochemical reaction between Nb 2 O 5 and Al. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry and scanning electron microscopy techniques. It was found that the reaction between Al and Nb 2 O 5 takes place in an explosive mode after about 450min of milling time. The milled powder had a microstructure consisting of nanocrystalline NbAl 3 base adjacent to Al 2 O 3 particles with a nanoscale grain size. At longer milling times, no changes were observed, except peaks broadening due to the decreasing in crystallite size and increasing in lattice strain. After 15h of milling time, average crystallite size of NbAl 3 and Al 2 O 3 were about 8 and 13nm, respectively. Heat treatment of powder mixture milled for 15h showed a good thermal stability for this nanocomposite.