A comprehensive overview to the rapidly emerging field of electron tomography (ET) for the study of heterogeneous catalysts and related nanostructured materials is presented. The study includes a detailed analysis of materials classes of zeolites, ordered mesoporous materials, disordered oxide supported catalysts, carbon materials, and miscellaneous materials such as ceramics, polymers, and nanocomposites. ET includes collecting a series of 2D images by tilting the specimen in the electron beam and recording an image at each tilt step. Common academic and commercial software packages are utilized for the alignment and reconstruction of ET data of these material samples. A detailed assessment of the validity for BF TEM ET shows that for weakly scattering materials where mass thickness is the dominant contrast mechanism, electron microscope images are essentially projections on which a tomographic reconstruction can be based.