In order to determine the extent to which the surface structures influence the diffusion behaviour of water at the interface of laser pre-treated AW 6082-T6 – E320 epoxy joints, an experiment based on µ-XRF analysis was designed and carried out. The laser pre-treated adhesive joints that were sealed off on all but one side were hydrothermally aged in a diluted solution of the chemical tracer SrBr2 in H2O at 80 °C. Cross-sections of aged joints with different laser pre-treatments were subsequently prepared and mapped with µ-XRF and the resulting diffusion lengths of strontium and bromine were determined. An analysis of these degradation experiments in the light of mechanical studies of the joint performances of differently pre-treated surfaces will be presented.