The Co-Mo oxide catalyst was modified with Ce, Cr and K ions by an impregnation method and treated with NH3 at 700 degrees C for 5 h. The contents of promoters, phase compn. and sp. surface of catalyst were detd. The catalyst were used for NH3 synthesis at 400 degrees C and 10 MPa and then subjected to aging at 650 degrees C for 12 h in order to assess their thermal stability. The effect of promoter concn. on the activity, sp. surface and content of cryst. phases of Co2Mo3N and Co2Mo3N were detd.