Certified reference materials (CRMs) are very important for the reliab
ility of the results of chemical analyses and, at the same time, const
itute the basis of comparability of analytical data. The development o
f a new type of CRMs is demonstrated using: the example of porous and
finely dispersed solids having specific surface al ea, specific pore v
olume, pore volume distribution, and mean pore radius as their charact
eristic values. Many of the properties of reference materials to be ce
rtified, such as their elemental content, are established by means of
measurement procedures relying on different and independent principles
of measurement. With porous or finely dispersed solids, however, the
characteristic values referring to pores strongly depend on the size o
f the probe molecules used, a fact which is due to the fractal charact
er oi. these substrates. This is particularly true for the specific su
rface area or tile pore volume. As a result, when applying the method
of gas adsorption. the certified values refer to a specific probe gas,
e.g. to nitrogen. The use of other gases yields different numerical v
alues for the characteristic values to be certified. Generally, the po
re system of a solid contains pores of irregular shape. Therefore, dep
ending on the presence of e.g, cylinder or slit pores, different evalu
ation models must be applied. For the verification of model calculatio
n of microporous solids, zeolites with their crystallographically defi
ned voids are particularly well suited. They can serve as a reference
point for the correctness of the model used.