Degradations and cyclodehydration of polyols in aqueous solution were studied on copper deposited on charcoal unmodified or modified by addition of chloride and a second metal (Pt or Au). These catalysts had properties very close to those of Raney copper based catalysts. Their deactivation was studied in a dynamic flow three-phase reactor. Sintering of copper particles, surface oxidation and copper(I) hydroxide dehydration were responsible for the deactivation of the unmodified Cu/C. In the cases of modified Cu/C, decrease of the cyclodehydration selectivity was attributed to the loss of chloride. Addition of chloride ions to the polyol solution to be converted increased the cyclodehydration selectivity but strongly decreased the activity.