This standard specifies a method for the determination of cobalt in steel and alloys using the potential Titrimetric method. It is suitable for alloy steels, superalloys and precision alloys. The determination range of cobalt is more than 3.00%. The method is carried out in an ammonia medium in the presence of ammonium citrate. Cobalt oxide is used in potassium ferricyanide. Excess potassium ferricyanide is used for back titration with cobalt sulfate standard solution. During the determination, the content of chromium, copper and manganese should be below the specified limit to avoid interference. The standard also lists the required reagents and the preparation method of the standard solution, including muriatic acid, nitric acid, ammonia water, ammonium citrate solution and cobalt standard solution.