Metallic effect pigments with a platelet-shaped metallic substrate. The pigments have at least one metal oxide layer. Covalently bonded to the surface of the metal oxide layer is a polysiloxane of formula I: where R1 is a saturated or unsaturated, straight-chain or branched alkyl radical having 1 to 30 carbon atoms and/or an aryl radical, alkylaryl radical or arylalkyl radical having 6 to 30 carbon atoms; R2, R3, R4 and R5 independently of one another are saturated or unsaturated, straight-chain or branched alkyl radicals having 1 to 6 carbon atoms and/or aryl radicals, alkylaryl radicals and/or arylalkyl radials having 6 to 12 carbon atoms; x=1 to 200, y=2 to 30; A is (CH2)n, O, S, (OCH2CH2)m or C6R64, where n=0 or 1 and m=0 to 30 and R6 is H and/or alkyl having 1 to 6 carbon atoms; B is (CH2)z or (OCH2CH2)w, z=0 to 30 and w=0 to 30; and R7 and R8 independently of one another are O or a saturated or unsaturated, straight-chain or branched alkyl radical having 1 to 6 carbon atoms and/or an aryl radical, alkylaryl radical or arylalkyl radical having 6 to 9 carbon atoms, where X is O or OH and is attached to the pigment surface. The disclosure further relates to a method for producing metallic effect pigments and to their use in powder coatings, more particularly in powder coatings produced by mixing methods, as well as to the use of these powder coatings. Finally, the disclosure also relates to powder coatings.