Oligo(phenylene ethynylene) (OPE) molecular junction has been suggested as a H-2 molecule sensor based on calculations using the first principles of density-functional theory and non-equilibrium Green's function. The electronic transport properties of the OPE molecule between two Au electrodes with or without adsorbed H-2 molecules are investigated. Results show that the adsorbed H-2 molecule significantly changes the characteristics of the current-voltage curve of the OPE molecular junction. The pure OPE molecular junction exhibits a significant negative differential resistance, but this kind of phenomenon will disappear or weaken after hydrogen molecules are adsorbed. The conductance of the junction also obviously decreases in the bias range of [-0.4, 0.4] V after adsorbing H-2 molecules. These effects can be used to design a H-2 molecule sensor. (c) 2018 Elsevier B.V. All rights reserved.