Porous carbon nanofibers (PCNFs) with controllable pore structures for removing low-concentrations of NO at room temperature were prepared from electrospun polyacrylonitrile nanofibersby oxidative stabilization, carbonization and steam activation. The PCNFs had high surface areas and abundant micropores, which were favorable for the adsorption and catalytic oxidation of NO at ambient temperature. The diameter of the fibers and their pore structure were tailored by adjusting the concentrations of polyacrylonitrile, and the spinning and activation parameters. Their performance in the removal of low-concentration NO was strongly dependent on their pore structure and fiber diameter. The highest NO removal ratio for PCNFs activated at 900 degrees C, which had an average diameter of 175 nm, reached 29.7% when the inlet NO concentration was 20 ppm.