Methanol decomposition to CO and H(2) on PdIn(110) has been studied by following the sequential dehydrogenation steps from CH(3)OH → CH(3)O → CH(2)O → CHO → CO using density functional theory slab calculations. The first three of the four elementary steps are strongly endothermic. The last step, i.e., CHO → CO + H, is almost thermal neutral. We also examined the effect of considering van der Waals interaction on the reaction energy and activation barrier of each elementary step by using the optB88-vdW and optB86b-vdW functionals. Our results show that both overall reaction energy and activation barrier were reduced by including van der Waals interactions but the qualitative picture remains unchanged.