The destruction of chlorinated hydrocarbons, such as carbon tetrachloride, over lanthanide-based solid catalysts in the presence of steam has been investigated between 200 and 350.degree. C. Ln.sub.2O.sub.3/AL.sub.2O.sub.3 (e.g. Ln=La, Nd, Ce and Pr) show a very high catalytic hydrolysis activity. The destruction capacity gradually increases with increasing temperature and reaches a maximum value of 42.310.sup.6 ppm.h.sup.-1 at 350.degree. C. for a 10 wt % Ln.sub.2O.sub.3/AL.sub.2O.sub.3 catalyst This destruction capacity could be maintained for a least 48 hours. The catalyst activity is also function of the type of lanthanide oxide; i.e., La.apprxeq.Nd>Ce.apprxeq.Pr. The process is based on a delicate equilibrium between destructive adsorption of CCI.sub.4 onto the lanthanide oxide and the dechlorination of the formed lanthanide chloride with steam. Steam being responsible for the in situ regeneration of the catalytic active phase.