Hydrodechlormation (HDC) of halons (halogenated hydrocarbons) such as ortho-dichlorobenzene (ODCB) and 1,2,4-trichlorobenzene (TCIBz) were carried out under vapor phase conditions at atmospheric pressure in a fixed-bed down flow tubular glass reactor using I'd supported catalysts. HDC of ODCB with H, gave benzene (Bz) as the major product with chlorobenzene (ClBz) as intermediate. The effect of parameters. such as. time-on-stream, flow rates of ODCB and H,, temperature, Pd loading and effect of supports (gamma-Al2O3, SiO2, carbon and MgO) were studied. HDC of TClBz using Pd/carbon gave high selectivity for ODCB. The reaction pathways of HDC of ODCB on Pd/gamma-Al2O3 was established and supported by empirical kinetic modeling. (C) 2002 Elsevier Science B.V. All rights reserved.