The catalytic behavior of Pd (2wt.%) catalysts supported on CeO 2 and promoted with La 2 O 3 was investigated for methanol decomposition. The addition of lanthana significantly improved the catalytic activity for methanol decomposition. Over LaPd/Ce-1.00 catalyst, a 100% conversion of methanol can be achieved at around 275 o C, which is about 40 o C lower than the temperature needed for Pd/CeO 2 . TPR results showed that the presence of lanthana shifted the reduction temperature of CeO 2 to lower values, while it hindered the reduction of PdO due to an accelerated diffusion of oxygen ions in the ceria-lanthana interface. Pd δ + -like species were formed on the catalyst surface due to the SMSI effect. Moreover, an increase of Pd δ + /Pd 0 ratio accompanied by the shift of the conversion profile to the lower temperature with increase of lanthana loading indicated that the low-temperature decomposition of methanol was very sensitive to the valence of palladium. The reasons for the formation of such Pd δ + -like species caused by lanthana addition are discussed in detail based on XRD, BET and XPS results. A simplified hypothesis about side reactions, which might occur during methanol decomposition to form by-products in this work, is also proposed.