The interaction between resorcinol formaldehyde latex adhesive (RFL) and polyester (PET) fiber was studied in the following manner: Indirectly by the determination of the cord-to-rubber bond strength change in dependence on the latex type in RFL; by determination of the swelling degree of RFL-films filled with PET fibers in dependence on fiber treatment, RFL composition and solvent nature; by IR-spectra of the model systems polyester film -resorcinol formaldehyde resin (RFR), latex polymer epoxy compound (EP), used for the adhesion activation of PET in the manufacture process, and RFR -EP.