Activated charcoal-dispersed Ru-Ir alloy nanoparticles (ca. 2.2 nm) are a selective and reusable hydrogenation catalyst for the conversion of 5-hydroxymethylfurfural to valuable liquid biofuel. A 99% yield to 2,5-dimethylfuran is achieved at only 120 °C. An acceleration in the reduction of substrate and intermediates is observed due to the synergistic effect between the Ru and Ir species.