The effect of atmospheric plasma treatment (APT) on the bonding performance of a cyanate ester and an epoxy carbon fiber reinforced composite fabricated with a polyester peel ply was evaluated. A room temperature (RT) cured epoxy, an elevated temperature cured epoxy, and a cyanate ester resin, were used as the bonding adhesives. Only small increases in the carboxyl species concentration were observed for both composite systems as a function of increasing plasma treatment. Lap shear (LS) tests of the bonded composites showed that the APT resulted in a 30% strength improvement for the RT cured epoxy bonded specimens while the cyanate ester composite exhibited negligible increases due to the formation of a highly oxidized, weakly bonded ash. Contact angle measurements indicated that the temperature exposure associated with the curing of the elevated temperature adhesives also reduced the efficacy of APT. Modifications of the bonding surface of these composites by the incorporation of a plasma responsive (PR) layer resulted in significant LS improvements. After incorporating the PR layer, the improvement in adhesive strength was over 225% that of an untreated specimen and approximately 190% that of the equivalently treated unmodified system. Bond strengths correlated with corresponding increases in carboxyl concentrations after APT. (C) Koninklijke Brill NV, Leiden, 2012