In the asphalt industry a substantial interest is observed to find possibilities to reduce the production temperature of asphalt mixtures. In the context of this research, new methods for the visualization of the unstable bitumen foam, like dynamic X-ray radiography, computed tomography (CT) and high speed camera investigations have been developed. Moreover characterization with empirical methods such as expansion ratio and half-life was determined accurately using ultrasonicmeasurements. This opens new possibilities to characterize the bitumen foam (foaming process) for practical applications.Examination of the foam bitumen stream using high-speed camera revealed that the foam bitumen contains fragmented pieces of bitumen, which resemble more a liquid than a foam. This indicates that the foam is formed afterwards and not, as assumed, within the expansion chamber of the foam generator. In situ thermal imagery of the surface, during the hot foaming process, showed that the temperature distribution depends on the foaming water content and bubble size distribution. Higher water content results in more inhomogeneous temperature distribution as compared to lower water content (< 2 w-%). The dynamic X-radiography results indicated that as the foam decays, the bubble size distribution becomes progressively larger with time for 160 °C bitumen temperature. Furthermore, at the beginning of the foam formation, the majority of the bubbles is small in cross-section size (0.2 -10 mm 2 ). At a later stage the bubbles become polydisperse. Moreover theoretical investigations based on the 3D X-ray CT scan dataset of bubble merging shows that the disjoining pressure increases as the foam film gets thinner with time and finally undergoes rupture. The speed of the bubbles also increases with time when the bubbles are getting closer to each other.