NOVELTY - The catalyst comprises an inorganic matrix with at least one perfluoroalkyl sulfonic groups covalently bonded to it.    USE - The catalyst is used in transformation processes for organic or inorganic compounds, especially esterification, acylation, alkylation or glycosidation reactions or a Beckmann rearrangement reaction. The esterification reaction involves reacting a stoichiometric amount of a fatty acid with a monovalent alcohol, diol or polyol, in order to prepare a jojoba oil analogue, a glycerol ester mixture, one or more kojic acid esters or one or more sorbitan esters. The alkylation reaction is a Friedel-Crafts reaction for alkylating benzene or its derivatives, using alkenes or alcohols as alkylating agents (preferably the alkylation of benzene with long chain linear alk-1-enes, especially dodec-1-ene), or it can involve the alkylation of isoparaffins or olefins, preferably the alkylation of isobutene using isobutane at a temperature less than 100 degrees C or the alkylation of olefins using alcohols as alkylating agents (especially for the preparation of methyl tert.-butyl ether). The acylation reaction is a Friedel-Crafts reaction or the acylation of anisole, 2-methoxynaphthalene or 4-methoxybenzene. The Beckmann rearrangement reaction is used to produce eta-caprolactam or dodecalactam. The catalyst can also be used as a component for a porous electrode for a fuel cell (claimed).    ADVANTAGE - The hybrid material has a higher intrinsic acidity and the perfluoroalkyl groups are more stable compared with non-perfluorinated alkyl sulfonic groups.    DETAILED DESCRIPTION - An acid catalyst is in the form of a solid organic-inorganic hybrid material comprising an inorganic matrix and one or more perfluoroalkyl sulfonic groups covalently bonded to the matrix via C-O-T bonds.    C = carbon;    O = oxygen; and    T = silicon or a metallic element.    An INDEPENDENT CLAIM is also included for the preparation of the catalyst by contacting the inorganic matrix with a fluorinated reagent containing at least one perfluoroalkyl sulfonic group and optionally containing one or more non-fluorinated sulfur-free alkyl groups.    DESCRIPTION OF DRAWING(S) - Figure 1 shows an X-ray diffraction pattern for MCM-41 powder and an acid catalyst comprising perfluoroalkyl-substituted MCM-41 powder.