The aerogel method, consisting of preparation of solid catalysts by sol-gel processes of organometallic precursors and drying the wet gel under hypercritical conditions, is a particularly interesting way to obtain highly divided materials for catalytic applications. Special attention is given to PbO ZrO 2 and PbO Al 2O 3 aerogel catalysts. Ordinary dried gels, i.e., the xerogels, are also interesting solids for catalysis. In this case, inorganic precursors can be utilized in the sol-gel stage and the resulting catalysts are compared to the characteristics exhibited by the corresponding aerogels in the case of alumina. XRD, BET and porosimetry analysis are used to determine their textural properties. The conversion of olefins into nitriles by NO (nitroxidation) in the presence of two PbO-based aerogel catalysts and the methylation of phenol with methanol on an amorphous, microporous alumina xerogel and on an alumina aerogel are examined.