In a process for converting C.sub.9+ aromatic hydrocarbons to lighter aromatic products a feed comprising C.sub.9+ aromatic hydrocarbons is contacted under transalkylation reaction conditions with a catalyst composition comprising (i) a first molecular sieve selected from the group consisting of ZSM-12, mordenite and a porous crystalline inorganic oxide material having an X-ray diffraction pattern including d-spacing maxima at 12.4.+-.0.25, 6.9.+-.0.15, 3.57.+-.0.07 and 3.42.+-.0.07; and (ii) a second molecular sieve having a constraint index ranging from 3 to 12. At least the first molecular sieve has a hydrogenation component associated therewith and the first and second molecular sieves are contained in the same catalyst bed. The C.sub.9+ aromatic hydrocarbons are converted under the transalkylation reaction conditions to a reaction product containing xylene.