Thin buffer layers of hydrogen diffusive metals such as Ti, Nb, and V were inserted between a Mg4Ni thin film and a Pd top layer, which were prepared by DC magnetron sputtering. Their optical, electrochemical properties, and switching durability were investigated using both gasochromic and electrochromic switching methods. It has been proved that Ti, Nb, and V buffer layers can protect the migration of Mg to surface of thin film during the switching processes, and also service as a protection layer against the oxidization of Mg. These metal buffer layers do not affect the hydrogenation of Mg-Ni alloy mirrors system when switching with hydrogen gas or electrochromic, rather, its dehydrogenation speed is accelerated greatly. Switching cyclic number of those metal buffer layer inserted mirrors achieved 400-500 cycles which was enhanced ca. 3 times than non-inserted one. (c) 2007 Elsevier B.V. All rights reserved.