A process for coating substrates, which comprises applying the reaction product obtained by the reaction of at least one polyorganosiloxane compound a) of the formula: Z[-X(-A-Y n) q] m wherein Z denotes a polyorganosiloxane unit, X denotes a chemical bond or an organic residue having 1 to 50 carbon atoms, wherein X is bond to a silicon atom of the polyorganosiloxane unit via a carbon atom, A denotes a hydrophilic polymeric unit, which may be the same or different unit in the compound of formula comprising as hydrophilic moieties those selected from poly-C 2 -C 4 -alkylene oxide groups, polyetherester groups, polyetheramide groups, polyoxazolidone groups, polyvinyl alcohol groups, homo- and copolymer groups that contain at least 50 wt % polymerized-in N-vinylpyrrolidone, homo- and copolymers that contain at least 30 wt % polymerized-in acrylamide and/or methacrylamide, homo- and copolymer groups that contain at least 30 wt % polymerized-in acrylic acid and/or methacrylic acid, or A denotes a hydrophilic polymeric unit, which may be the same or different unit in the compound of formula selected from polyether groups, Y is selected from -OH, -SH, -NH 2, and -NHR 4, wherein R 4 is hydrocarbyl group having up to 10 carbon atoms, q is from 1 to 5, m is from 3 to 100, n is from 1 to 5, and at least one polyisocyanate b), with the proviso that the molar ratio of the components a) and b) is such that the reaction product contains reactive isocyanate groups, or a polyorganosiloxane-polyisocyanate of the formula: Z{-X[-A-[Y'-C(=O)-NH-E- p] n] q} m wherein the group Z, X, A, q, m, n are each as defined above, Y' denotes a group derived from the addition of the group Y to the NCO-group, E denotes an organic residue, p is from 1 to 5, onto a substrate and curing the reaction product to obtain a coating onto the substrate. Z denotes a polyorganosiloxane unit, X denotes a chemical bond or an organic residue having 1 to 50 carbon atoms, wherein X is bond to a silicon atom of the polyorganosiloxane unit via a carbon atom, A denotes a hydrophilic polymeric unit, which may be the same or different unit in the compound of formula comprising as hydrophilic moieties those selected from poly-C 2 -C 4 -alkylene oxide groups, polyetherester groups, polyetheramide groups, polyoxazolidone groups, polyvinyl alcohol groups, homo- and copolymer groups that contain at least 50 wt % polymerized-in N-vinylpyrrolidone, homo- and copolymers that contain at least 30 wt % polymerized-in acrylamide and/or methacrylamide, homo- and copolymer groups that contain at least 30 wt % polymerized-in acrylic acid and/or methacrylic acid, or A denotes a hydrophilic polymeric unit, which may be the same or different unit in the compound of formula selected from polyether groups, Y is selected from -OH, -SH, -NH 2, and -NHR 4, wherein R 4 is hydrocarbyl group having up to 10 carbon atoms, q is from 1 to 5, m is from 3 to 100, n is from 1 to 5, the group Z, X, A, q, m, n are each as defined above, Y' denotes a group derived from the addition of the group Y to the NCO-group, E denotes an organic residue, p is from 1 to 5, onto a substrate and curing the reaction product to obtain a coating onto the substrate.