Experimental investigations of an adhesively bonded riveted joint between a glass-fibre reinforced unsaturated polyester composite (GUP) and an aluminium alloy are presented in the paper. The study is focused on a novel test method, that combines destructive and non-destructive methods in a so called in-situ computed tomography (CT) analysis. The aim of the investigations is to identify different modes and locations of failure in a combined joint during quasi-static loading by simultaneous X-ray computed tomography. The combined method provides a deeper understanding of the failure and damage processes in the joining area. Different variations of a single-lap joint with varying adhesive layer thicknesses and different fasteners are examined. The in-situ CT tests are used to gain a phenomenological basis for a subsequent cross-scale modelling of the complex damage behaviour. By a combination of load and unload stages during the experiments and intermittent CT analyses, the crack initiation and the crack propagation can be detected.