The present work studies the cohesive behaviour of a previously proposed novel direct bonding method for dissimilar bonding between a carbon fibre reinforced thermoplastic (CFRTP) and aluminium. A nanostructure is manufactured on the aluminium surface and is directly bonded to the CFRTP by applying heat and pressure. Double cantilever beam (DCB) testing is carried out to evaluate the bonding properties and the initial results of a method for directly measuring the traction-separation behaviour from experiments is presented. The nanostructure is observed to improve the bonding properties significantly compared to two other considered bonding cases. Furthermore, the measured traction-separation behaviour is seen to be difference for each case. Nevertheless, the applied calculation method shows some challenges related to thermal stresses and plastic deformation that should to be taken into account in future studies.