A one dimensional spring model has been developed for a thermally loaded composite/aluminium joint. The thermal force on the outer fasteners in a generic joint between an inner aluminium wing and the outer composite wing is about 8 kN when the temperature of the complete structure is increased with 100 oC. Similar thermal force is obtained in a two-fastener joint if the distance between the fasteners is about 0.2 m. The thermal force on the fasteners will be perpendicular to the applied mechanical load and the resulting force will affect both the aluminium and composite. This will cause the damage zones to move slightly compared to the case of no thermal force. Secondary bending reduces the fatigue life of aluminium joints and should be minimized. This can be done by increasing the bending stiffness of the joint, decreasing the free length of the joint, or by using buckling supports during testing. A method to design a simple climate chamber for heating and cooling is described. Possible test parameters for the test program are listed and the joints should be designed such that some joints fail in the aluminium and some in the composite.