(A.) A process for forming a cobalt conversion coating on a metal substrate, thereby imparting corrosion resistance and paint adhesion properties. The invention was developed as a replacement for the prior art chromic acid process. The process includes the steps of: (a) providing a cobalt conversion reaction solution comprising an aqueous, alkaline solution containing a soluble cobalt-III hexacoordinated complex, the concentration of the cobalt-III hexacoordinated complex being from about 0.1 mole per gallon of solution to the saturation limit of the cobalt-III hexacoordinated complex; and (b) contacting the substrate with the aqueous reaction solution for a sufficient amount of time, whereby the cobalt conversion coating is formed. The substrate may be aluminum or aluminum alloy, as well as Cd plating, Zn plating, Zn--Ni plating, and steel. The cobalt-III hexacoordinated complex may be present in the form of [Co(NH.sub.3).sub.6 ]X.sub.3 wherein X is Cl, Br, NO.sub.3, CN, SCN, 1/3PO.sub.4, 1/2SO.sub.4, C.sub.2 H.sub.3 O.sub.2, or 1/2CO.sub.3. (B.) A chemical conversion coating solution for producing a cobalt conversion coating on a metal substrate, the solution comprising an aqueous, alkaline reaction solution containing a soluble cobalt-III hexacoordinate complex, the concentration of the cobalt-III hexacoordinate complex being from about 0.1 mole per gallon of solution to the saturation limit of the cobalt-III hexacoordinate complex. The aqueous reaction solution may be prepared by a bath makeup sequence including the steps of: (a) dissolving an ammonium salt; (b) then dissolving a cobalt-II salt; and (c) then adding ammonium hydroxide (ammonia). (C.) A coated article exhibiting corrosion resistance and paint adhesion properties, the article including: (a) a metal substrate; and (b) a cobalt conversion coating formed on the substrate, the cobalt conversion coating including aluminum oxide Al.sub.2 O.sub.3 as the largest volume percent, and cobalt oxides CoO, Co.sub.3 O.sub.4, and Co.sub.2 O.sub.3.