Traditional methods for examining clinch joining are limited, as the joining zone is hard to access and often requires destructive preparation, which can alter or hide critical phenomena. As a result, important processes like elastic-plastic deformation, crack closure or fiber reorientation in composites remain largely unseen. The presentation introduces a method for non-destructive, high-resolution analysis of clinching joints using in-situ X-ray computed tomography (CT). For the first time, this allows detailed three-dimensional observation of deformation and damage mechanisms during both the joining process and subsequent loading. Technical innovations include specialized tools and adapters for precise measurements, as well as methods to reduce imaging artifacts. This enables a new level of detail in the analysis of joining processes, which supports a better understanding and further development of reliable and efficient mechanical joining methods.