A spectrophotometric method for the determination of cobalt in 18/8 steel is described. Iron is removed by solvent extraction, cobalt is separated by means of an ion-exchange resin and converted to the nitroso-R-salt complex, the optical density of which is then measured. The method can be applied on the macro- and on the micro-scale. The limit of error lies between 4 and 6%; the limit of identification is 0.005 μg cobalt. A less sensitive (0.5 μg/ml) but more rapid polarographic method is also described.