The promotional role of Zn in hydrodeoxygenation (HDO) reactions of 5-hydroxymethyl furfural (HMF) to produce 2,5-dimethyl furan (DMF) over the Pd catalyst was studied using plane-wave density functional theory (DFT) calculations. HMF is first hydrogenated to form bis(hydroxymethyl) furan (BHMF), which undergoes HDO to form DMF. In order to provide a mechanistic explanation to the experimental observation, DFT calculations focusing on the energetics of the HDO reaction steps for BHMF conversion to DMF were performed on three different surfaces: Pd(111), Pd(211), and PdZn(211). Zn was assumed to preferentially substitute the defect sites of the bimetallic catalyst in reduced metallic state. Calculated values of activation energies for C-O dissociations steps were significantly reduced on the PdZn(211) surface, compared to the Pd(111) and Pd(211) surfaces. Therefore, theoretical results provided a clue to the reactivity of the Zn-decorated step sites for the HDO reaction.