Bimetals prepared by addition of a noble metal (Ru, Pt, Au, Pd) on Raney copper catalyze very selectively the cyclodehydration reaction of polyols into furanic derivatives (e.g. sorbitol into isosorbide) whereas the pure metals catalyze the cleavages of CC and CO bonds (Cu, Ru) or are inactive (Pt, Au, Pd). The influences of the reaction conditions on the cyclodehydration kinetics, as well as those of the preparation conditions of these bimetals in connection with their physicochemical properties, were studied. It appears that the cyclodehydration sites involve copper, noble metal and halogen, this last element coming from the precursor salt used during the modification of Raney copper. Lack of one of these two last elements: noble metal without halogen or halogen without noble metal, does not allow the complete removal of the hydroxylated sites responsible for the degradation reactions.