Catalytic synthesis of propionitrile from methanol and acetonitrile was achieved by using activated-carbon-supported sodium catalysts. The activity of catalysts is determined by the precursor of the sodium: the catalysts prepared from sodium hydrogen carbonate show the highest activity. At high conversion of acetonitrile (70%), a propionitrile yield selectively exceeding 80% is achieved with a minor amount of methacrylonitrile as a secondary product. The order of catalytic activity of catalysts correlates well with the adsorption capacities for methanol and acetonitrile measured by the TPD method.