Pyrogenically produced aluminum-silicon mixed oxides with a BET surface of more than 300 m.sup.2/g and a composition of 0.01 to 99.99% by wt. AI.sub.2O.sub.3, remainder SiO.sub.2 are produced in accordance with the method of flame pyrolysis or preferably flame hydrolysis by a joint combustion of the gaseous raw substances. They can be used to produce coating colors, especially for inkjet papers or inkjet foils or other inkjet materials.