The deactivation of the palladium catalyst supported on activated carbon (Pd/C) was investigated in the repeated runs of the catalytic hydrodechlorination (HDC) of tetrachloroethylene (PCE) in pure MeOH and in 50/50 water-MeOH mixture with catalyst and solvent reuse at 20 degrees C and atmospheric pressure. Faster PCE dechlorination rates and slightly slower catalyst deactivation were observed in the runs in the mixture than in those in pure MeOH. Washing by stirring in either water or MeOH could completely recover the initial activity of the catalyst repeatedly used in the mixture, but could only partially recover that of the catalyst repeatedly used in pure MeOH. These results clearly show the superiority of using a 50/50 water-MeOH mixture over pure MeOH as a solvent for the HDC of PCE. (c) 2006 Elsevier B.V All rights reserved.