Fractal and aggregate structures of porous materials were studied by a variety of the structure characterization techniques (TEM, small angle X-ray scattering, nitrogen sorption). Scattering data (SAXS, USAXS) for porous materials measured with laboratory equipment and synchrotron technique were interpreted in terms of Guinier, Emmerling, Freltoft, modified Freltoft theories, and simple power law expressions. The evaluation of scattering measurements resulted in fractal dimensions, sizes of the elementary units, the fractal domains or the aggregates. TEM images confirmed the sizes of the elementary building units, while the pore size distributions could be obtained by nitrogen adsorption. The specific surface area was calculated with respect to the possibility of multilayer formation during nitrogen absorption.