Supported cobalt catalysts were synthesised, characterised (by H-2 TPD, XRD, TEM), and tested in ammonia synthesis at 9.0 MPa (400-470 degrees C; H-2:N-2 = 3:1). Partly graphitised carbon of high surface area (840 m(2)/g), cobalt nitrate, and barium nitrate were used as a support, a precursor of the active phase, and a promoter precursor, respectively. Both cobalt dispersion in the Ba-doped catalyst and, to a greater extent, catalytic properties of the promoted Co surfaces (TOF) proved to be dependent on the unpromoted material pretreatment (reduction in H-2, subsequent calcination in air). The kinetic studies of NH3 synthesis have shown explicitly that Ba-promoted cobalt on carbon is very active and less inhibited by the ammonia product than the commercial magnetite-based material. (c) 2005 Elsevier Inc. All rights reserved.