1. Alkali-thiocyanate is a sensitive reagent for the detection of cobalt in presence of 40 to 50% acetone. Ferric iron can be made harmless by addition of an excess of fluoride. A procedure has been developed for the application of the reaction as a micro-and macro test for cobalt. Cupric copper gives a sensitive reaction and must be removed. The thiocyanate is preferable to cyanate as a reagent. 2. A procedure has been described for the micro detection of thiocyanate by evaporating a drop of the solution to be tested with a small drop of cobalt sulfate and moistening the residue with acetone. The formation of a distinctly green solution indicates the presence of thiocyanate. Nitrite interferes.