The purpose of this study is to determine the influence of boron addition on the oxidation resistance of MoSi2. Powder mixtures of Mo-Si with stoichiometric ratio of 1:2 and 30Mo-47Si-23B (at.%) were used, respectively to produce MoSi2 and MoB/MoSi2. First powder mixtures were separately milled for 20 h in an attritor ball mill. After degassing of as-mechanically alloyed powders at 450 degrees C, the powders were pressed into cylindrical samples under a pressure of 600 MPa. The final diameter of samples were 15 mm. Compacted samples were sintered in tube resistance furnace using Ar controlled atmosphere. 30Mo-47Si-23B alloy with a MoB/MoSi2 two-phase structure and monolithic MoSi2 were obtained by sintering at 1300 degrees C for 3 h and 1100 degrees C for 7 h, respectively. The sintered alloys were subjected to high temperature continuous oxidation test at 1000 degrees C. Microstructure of sintered alloys and as-mechanically alloyed powders, phase composition of sintered and oxidized samples were evaluated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results showed that in 30Mo-47Si-23B alloy no pest disintegration is observed. The presence of boron acted as an effective barrier against oxygen diffusion during oxidation test of MoB/MoSi2 composite. Excellent oxidation resistance of MoB/MoSi2 composite was achieved through homogeneously distributed and fine grained microstructure and also very high relative density. (C) 2014 Elsevier B.V. All rights reserved.