The adsorption and dissociation behaviors of methanol on Pd(111),Pd/Au(111)and Pd/Rh(111)surfaces were studied using a periodical slab model and the PW91 generalized gradient approximation(GGA)within the framework of first-principles calculations based on density functional theory(DFT).The adsorption energy and geometric parameters for the three surfaces showed that methanol is preferentially adsorbed onto the top-Pd sites and that the adsorption energy of methanol on these surfaces decreases in the order Pd/Au(111)＞ Pd/Rh(111)＞Pd(111).After adsorption,the C-O,C-H and O-H bonds in methanol adsorbed onto these surfaces are elongated and the vibrational stretching frequency of the O-H bond is obviously redshifted.Furthermore,the first step for the possible dissociation pathway formethanol on these surfaces was calculated.Our results indicate that the O-H bond in methanol decomposes producing methoxy and a hydrogen atom,with the Pd/Au(111)surface exhibiting the smallest dissociation barrier.