Activity of carbon based ruthenium catalysts promoted with alkaline earth metal ions (Mg, Sr, Ba) has been studied. The thermally modified active carbon (1900 degrees C, helium) was used as a support of the catalysts. Ruthenium chloride was used as a precursor of the active phase. Activity measurements in the process of ammonium synthesis were curried out at 6 MPa. Barium was found to be the most effective promoter among studied ones, particularly if introduced as nitrate. Barium promoted Ru/C catalyst exhibited several times higher reaction rate than fused industrial iron catalyst, particularly at high conversions.