Evaluation of the long-term radionuclide release from cemented waste forms in contact with solutions like salt brine requires a detailed chemical analysis of the corrosion processes. The results can be integrated into a theoretical model. For this purpose, experiments were performed with simulated cemented radioactive waste forms, giving the concentration profiles of the elements involved in the corrosion process. The profiles are measured parallel to the direction of corrosion, mainly by electron microprobe analysis. The profiles are compared with profiles computed with the recently developed DIFMOD computer code. It computes both leaching of specimen transportation of the reactive ions, such as Mg2+ and contained in a quinary brine, into the cement product and the chemical reactions occurring in the waste form. On the basis of diffusion constants from the literature and fitted material constants, a good agreement between the calculated and measured concentration profiles has been achieved. The penetration of the corrosion front into waste forms is computed as an example of a practical application of the model.