Quantitative autoradiography for the investigation of rock matrices has been further developed by use of tritium-labeled polymethylmethacrylate (3H-PMMA), the use of thin sections and image analysis functions allowing correlations of mineralogic-petrographical and analytical or porosity information. The autoradiographic system was studied experimentally and theoretically. The autoradiography could achieve a resolution down to 10 and 20 μm for 3H and 14C, respectively. Possible candidates for intact, low-porous rock standard materials were studied and the measurement of their transport properties discussed. Porosities and diffusivities measured in rock types dominated by very small pores were depending on the probe molecule used. The effect was most pronounced in flint which gave low porosities for MMA, Hg and He and no diffusivities at all for He.