There is widespread use of two main groups of adhesion promoters, the SRH-system and an organic cobalt salt. They are used either jointly or individually in the rubber compound for promotion and maintenance of good adhesion of rubber to brass-coated steel cord in radial tyres. This paper describes the influence of anions associated with cobalt promoters on the adhesion energy and the pull-out force between brass-coated steel cord and rubber and their relationship to other relevant physical properties, under the influence of various environments which simulate tyre service conditions. It is observed that incorporation of a cobalt promoter greatly enhances the adhesion energy and influences the Young＇s modulus and crosslink density of the rubber compound in a similar fashion. The study establishes the supremacy of boroacylate among the anions considering its overall good performance and the protection offered against various hostile environments. However, the benefits of the cobalt promoter is not realised with stearate ion. The results are explained on the basis of chemical stability of the promoter and the properties of the interfacial film and the compounds.