In this paper a new aqueous bonding system is described for the adhesion of EPDM-rubber to stainless steel, Water-soluble polymeric coupling agents are proposed, obtained by chemical modification of poly(acrylic acid). The synthesis of the water-soluble polymers and their characterisation and testing with the ISO-5600 standard test are discussed, An autoclave test at 135 degrees C in a 50/50 % water-glycol mixture was performed with stainless steel-EPDM joints. By using a coupling agent with carboxylic acid, hydroxamic acid and allylglycidyl ether groups the joints can successfully withstand the autoclave test for 22 h.