TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The catalytic hydrodealkylation reaction is carried out in the presence of water, previously vaporized and mixed with the hydrocarbon fraction in gas phase before the reactor inlet, or added to the liquid hydrocarbon fraction until its saturation at room temperature, or by means of a compound miscible with the charge and capable of releasing it during the reaction.The compounds capable of releasing water and generating aliphatic and/or aromatic hydrocarbon species of the same nature as those present in the liquid and gaseous phase of the reaction are alcohols, ethers and/or esters. The compounds are ethanol or phenethyl alcohol. The molar ratio between water and charge in the feeding to the reactor (ranges from 0.0006-0,16 (i.e. 0.01-2.5% w/w) (preferably 0.003-0.032 (i.e. 0.05-0.5% w/w)). The hydrodealkylation reaction takes place at 450-600degreesC, pressures from 2.8-3.6 MPa, hydrogen/charge molar ratios from 3.8-5.2, and with such reagent flow-rates as to guarantee an liquid hourly space velocity (LHSV), calculated on the hydrocarbon stream, ranging from 3-5 h-1 (preferably 3.5-4.5 h-1).Preferred Compounds: The hydrocarbon charge subjected to hydrodealkylation comprises 8-13C alkylaromatic compounds of ethylbenzene, xylenes, propylbenzenes, ethyltoluenes, trimethylbenzenes, diethylbenzenes, ethylxylenes, tetramethylbenzenes, propyltoluenes, ethyltrimethylbenzenes, triethylbenzenes or dipropyltoluenes.The 8-13C alkylaromatic hydrocarbon charge derives from reforming units or from units, which effect pyrolytic processes, or from steam-cracking. The hydrocarbon charge subjected to hydrodealkylation comprises 8-13C alkylaromatic compounds optionally mixed with 4-9C aliphatic and cycloaliphatic products and organic compounds containing hetero-atoms.Preferred Catalyst: The catalyst consists of a ZSM-5 zeolite in bound form with binders of aluminas (pseudo-bohemite and gamma-alumina), clays (kaolinite, smectites or montmorillonites), silica, aluminosilicates, titanium and/or zirconium oxides with zeolite/binder weight ratios of 100/1-1/10. The ZSM-5/binder catalyst is modified with at least one metal of those belonging to Groups IIB, VIB or VIII. The metal is molybdenum. The ZSM-5 zeolite is characterized by a silicon/aluminum molar ratio 15-30. The dispersion of metals on the catalyst is effected to techniques of impregnation, ion exchange, vapor deposition or surface adsorption. The ZSM-5 zeolite as such or in bound form is impregnated with metals of Groups IIB, VIB or VIII according to the method comprising preparing one or more solutions of compounds of the metals to be carried, impregnating the zeolite with the above solutions, drying the zeolite thus impregnated, calcining the zeolite, impregnated and dried at 400-650degreesC, and possibly repeating the above steps several times. The dispersion of the metals on the catalyst takes place by impregnation with an aqueous or aqueous-organic solution, the organic solvent is alcohols, ketones and/or nitriles, containing at least one hydro- or organo-soluble compound of the metal in such concentrations that the total final content of the metal in the catalyst ranges from 0.1-10 wt.%. The total metal content in the catalyst ranges is 0.5-8 wt.%.