NOVELTY - Performing subsequent surface modification of a structure of a hard, inorganic material, comprises treating the fabric with an organic liquid containing at least a reactive substance, which is reacted to form a chemical bond with atoms of the inorganic material, and at least one reactive functional groups including hydroxyl group, carboxyl group, carbonate group and P-atom linked oxygen atoms, where the treatment is carried out under conditions, in which the organic liquid is present under supercritical conditions.    USE - The method is useful for performing subsequent surface modification of a structure of a hard, inorganic material such as silica oxide, zinc oxide, tin(IV) oxide, titanium(IV) oxide and aluminum oxide (all claimed), which is useful as catalyst support materials in fuel cells, and gas storage materials for active compounds and effect release of substances in filtering systems, textile industry and electronics industry.    ADVANTAGE - The method performs subsequent surface modification of the structures of the hard, inorganic material with high space-time yield to produce larger quantities surface-modified fine-textured inorganic structures with improved mechanical stability, electrical conductivity, hydrophilicity/lipophilicity, adsorption capacity or optical properties and without damage in a cost effective manner.    DETAILED DESCRIPTION - Performing subsequent surface modification of a structure of a hard, inorganic material, comprises treating the fabric with an organic liquid containing at least a reactive substance, which is reacted to form a chemical bond with atoms of the inorganic material, and at least one reactive functional groups including hydroxyl group, carboxyl group, carbonate group and P-atom linked oxygen atoms, where the treatment is carried out under conditions, in which the organic liquid is present under supercritical conditions. The structure in at least one spatial direction has a material thickness M of 1000 nm, where the dimension of the structure in the spatial direction is at least 5 times than that of the material thickness. An INDEPENDENT CLAIM is included for forming the hard, inorganic material.