Orbital and spin moments of Co atoms in films of different thickness deposited by magnetron-sputtering on silicon wafers have been investigated by use of soft x -ray magnetic circular dichroism in absorption. Layers with thickness 2nm, 10nm and 30nm are covered by 0.8—1nm of protection overlayer. Orbital and spin momen ts of 0.249—0.195μB and 1.230—1.734μB are found from X MCD sum rules. Increase in orbital moments and decrease in spin moments are obse rved with reducing cobalt film thickness. There is a ratio variation from 0.101 to 0.168 of orbital moment to total moment, that is, contribution of orbital mom ent of cobalt atoms to total moment in 2nm film is 83% greater than that in the 30nm film.