A measurement apparatus for observing the foaming of metals is described. It consists of a microfocus X‐ray source, a small heater and a panel detector. The foaming of samples can be recorded in real‐time with frequencies up to 9 Hz and resolutions down to 5 μm due to the small spot size. Magnifications up to 10x are obtained by simply changing the distance between source, sample and detector. Foaming of Al alloys and sandwiches was investigated applying different final foaming temperatures, heating rates and blowing agent pre‐treatments. An image analysis program was developed to automatically recognise the foam expansion. A measurement apparatus for observing the foaming of metals is described. The foaming of samples can be recorded in real‐time with frequencies up to 9 Hz and resolutions down to 5 μm due to the small spot size. Magnifications up to 10× are obtained by simply changing the distance between source, sample and detector. Foaming of Al alloys and sandwiches was investigated and an image analysis program was developed to automatically recognise the foam expansion.