Benzhydryl derivatives of the formula I, where the index and the variables are as defined below: X is oxygen or sulfur; R1, R3 are halogen, cyano, nitro, hydroxyl, mercapto, amino, alkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, alkylcarbonyloxy, formyloxy, alkylthio, alkenylthio, alkynylthio, alkylamino, dialkylamino, alkylcarbonyl or formyl, where the carbon atoms in the radicals mentioned may be partially or fully halogenated; R2 is halogen, cyano, nitro, hydroxyl, mercapto, amino, alkyl, alkoxy, haloalkyl or haloalkoxy, where the groups R2 may be different if n=2; R4 is alkyl, alkenyl or alkynyl, where the carbon atoms in these radicals may be unsubstituted or partially or fully halogenated; R5, R6 are hydroxyl, alkyl, alkenyl, haloalkyl, haloalkenyl, alkoxy, alkenyloxy, haloalkoxy, haloalkenyloxy, cycloalkyl, cycloalkylalkyl, cycloalkoxy or cycloalkylalkoxy; n is 0, 1 or 2; processes for preparing the compounds I, compositions comprising them and their use for controlling phytopathogenic harmful fungi are described.