Pulsed thermal imaging has been widely used for nondestructive evaluation of engineering materials. Development of advanced data processing methods has improved the capabilities of this technology. However, many limitations still present. Current data‐processing methods intended for property measurement are mostly based on mathematical models that are only related to gross material properties such as thickness‐averaged thermal diffusivity or sample thickness (or defect depth). These models cannot account for material property variations within the sample volume. On the other hand, data‐processing methods intended for internal‐flaw detection are usually not suitable for inspection of complex material systems. In addition to these fundamental issues, a prior knowledge for some parameters of the tested material is normally required in order to perform data processing with an appropriate model or to interpret result. These problems can all be addressed by a recently‐developed thermal tomography method. It utilizes the one‐sided flash thermal‐imaging data to construct three‐dimensional data of material’s thermal effusivity in the entire sample volume. This paper discusses the theories and presents typical results obtained by this method.