Process for cross-coupling aromatic boron compounds with aromatic halogen compounds or perfluoroalkylsulfonates.In a process for preparing polycyclic aromatic compounds by cross-coupling aromatic boron compounds with aromatic halogen compounds or perfluoroalkylsulfonates under palladium catalysis in the presence of at least one water-soluble complex ligand, the reaction medium comprises an aqueous and an organic phase and the palladium is added in the form of a palladium compound soluble in the organic phase.Polycyclic aromatic compounds can thus be prepared economically and in very good yields and simultaneously very high purity, in particular without contamination by the complexing ligands.