Adhesive bonding is a highly desirable joining technique to join composites to metals. The surfaces of both composite and metal substrates have to be carefully treated before bonding them together, in order to avoid interface failure between the adherend's surface and adhesive. This paper describes the surface pretreatments on carbon fiber reinforced plastic (CFRP) and Titanium for the manufacturing of adhesively bonded CFRP-Titanium joints. Different treatments were applied in order to roughen and activate both substrate surfaces. The quality of the surface pretreatment using different treatment methods was initially checked by contact angle measurements. Destructive tests on the bonded specimens after various surface pretreatments, including those which provided the lowest contact angle, were performed to validate the mechanical performance of the surface treatment on the bond quality. The test procedure and results on adhesively bonded CFRP-CFRP specimens and Titanium-Titanium specimens will be presented and discussed. 100% cohesive failure in both CFRP-CFRP and Titanium-Titanium joint types guarantees the high quality of the adhesively bonded joints, and proves that the respective surface pretreatments on CFRP and Titanium excludes adhesive failures in bonded CFRP-Titanium joints.