The adhesion properties between rubber compounds with different amounts of cobalt salt and Sulfur and ternary-alloy-coated steel cord with 2 wt% cobalt plating amount were investigated to understand the effects of cobalt salt and Sulfur in rubber compounds on their adhesion characteristics to the ternary-alloy-coated steel cord. The adhesion properties of the rubber compounds to ternary-alloy-coated steel cord were largely dependent on the amounts of both cobalt salt and sulfur in the rubber compounds. The pull-out force of adhesion sample increased significantly with increasing concentration of cobalt salt in the rubber compound with constant sulfur loading, while it decreased slightly with increasing sulfur into the rubber compound with constant cobalt salt loading. Adhesion retention after various hostile aging treatments improved in the rubber compounds incorporating both cobalt salt and high loading of sulfur. The interphases between the rubber compounds and the ternary-alloy-coated steel cord studied using AES showed stable adhesion patterns by incorporating cobalt salt, resulting in enhancement of the adhesion retention.