Palladium (Pd) nanoparticles stabilized by polyethylene glycol were incorporated into polybenzimidazole (PBI) to form a mixed-matrix membrane (MMM) for hydrogen (H-2) purification. Energy dispersive X-ray results confirmed the existence of Pd nanoparticles in the PBI matrix. These dense membranes showed a homogeneously dispersed morphology in scanning electron microscope images that proves the excellent interphase affinity between PBI matrix and Pd nanoparticles. Unlike Pd membranes, the PBI(Pd) MMMs interact with H-2 starting from a low temperature as indicated in temperature-programmed reduction analysis. At elevated operating temperature, the PBI(Pd) MMM exhibited a higher selectivity compared to the neat PBI membrane. The PBI(Pd) MMM also surpassed the Robeson plot which represents the permeability/selectivity trade-off.