Abstract: The invention relates to saponite-derivatives according to the general formulaA.sub.x/n.sup.n+ [(Mg.sub.3-y M.sub.y) (Si.sub.4-x Al.sub.x)0.sub.10 (OH.sub.2-z)F.sub.z ]wherein A represents an (alkyl-substituted) ammonium ion and/or any metal having basic or amphoteric properties, M represents a bivalent metal ion having an ionic radius between 0.050 and 0.085 nm, n represents the valence of A, x represents a number between 0.05 and 1.5, y represents a number between 0.05 and 2.95 and z represent a number from 0 to 1.8. The invention also relates to methods for preparing such saponite-derivatives, catalytically active system based on such saponite-derivatives and their use in various hydrocarbon conversion processes.