Abstract: A method is disclosed for improving the hydrolytic stability of the adhesive bond between an RFL type organic adhesive and the steel reinforcing element in steel-rubber composite articles. This is accomplished by a pre-treatment of the steel surface before it is coated with the organic adhesive. The pre-treatment is conducted in a continuous operation which includes the sequential steps of: (1) cleaning the metal surface by a vapor degreasing method or by immersion in a detergent containing aqueous bath followed by a hot water rinse; (2) coating the surface with a crystalline or microcrystalline zinc phosphate; (3) rinsing the phosphated steel surface with water; (4) subjecting the phosphated surface to a chromate or chromic acid rinse; (5) rinsing again with deionized water; and finally (6) drying the steel reinforcing element.