A process for preparing substituted biphenyls of the formula I in which the substituents are defined as follows: X is fluorine or chlorine; R1 is nitro, amino or NHR3; R2 is cyano, nitro, halogen, C1-C6-alkyl, C1-C6-alkenyl, C1-C6-alkynyl, C1-C6-alkoxy, C1-C6-haloalkyl, C1-C6-alkylcarbonyl or phenyl; R3 is C1-C4-alkyl, C1-C4-alkenyl or C1-C4-alkynyl; n is 1, 2 or 3, where in case that n is 2 or 3, the R2 radicals may also be different, which comprises reacting the compound of the formula II in which Hal is halogen and X and R1 are as defined above, in the presence of a base and of a palladium catalyst selected from the group of: a) palladium-triarylphosphine or -trialkylphosphine complex with palladium in the zero oxidation state, b) salt of palladium in the presence of triarylphospine or trialkylphosphine as a complex ligand or c) metallic palladium, optionally applied to support, in the presence of triarylphosphine or trialkylphosphine, in a solvent, with a diphenylborinic acid (III) in which R2 and n are as defined above, where the triarylphosphines or trialkylphosphines used may be substituted.