A process for transalkylation of an alkyl-aromatic hydrocarbon feedstock that has at least 9 carbon atoms per molecule that comprises a) the introduction of said alkyl-aromatic hydrocarbon feedstock at the inlet of a first reaction zone where it is brought into contact with at least a first zeolitic catalyst, b) the introduction of at least a portion of the effluent that is obtained from stage a) and a feedstock that contains benzene and/or toluene at the inlet of a second reaction zone that contains at least a second zeolitic catalyst, and c) the separation of at least a portion of the effluent that is obtained from stage b) is described.