Process for preparing hydroxyaromatics

A process for preparing hydroxyaromatics comprising reacting aromatics of the formula (I)

• Ar—Rn (I)
• wherein
• Ar represents benzene or naphthalene,
• R represents Br, Cl, F, NO2, CN, NH2, OH, C1-C6-alkyl, or phenyl, and
• n denotes zero, 1, or 2,
• with dinitrogen monoxide in the gas phase in the presence of zeolites selected from the group consisting of pentasils, ferrierite and zeolite-β wherein the zeolites have a crystallite size <100 nm and are calcined at temperatures of 500 to 1350° C. before use.