Formaldehyde (HCHO) is an air pollutant suspected of being carcinogenic and a cause of sick-house syndrome. Microorganisms called methylotrophs, which can utilize reduced C(1) compounds such as methane and methanol, fix and assimilate HCHO, whereas most plants are unable to assimilate HCHO directly. We found that a bacterial formaldehyde-fixing pathway (ribulose monophosphate pathway) can be integrated as a bypass to the Calvin-Benson cycle in transgenic Arabidopsis thaliana and tobacco by genetic engineering. These plants showed enhanced tolerance to HCHO and enhanced capacity to eliminate gaseous HCHO by fixing it as a sugar phosphate. Our results provide a novel strategy for phytoremediation of HCHO pollution, and also represent the first step toward the production of plants that can assimilate natural gas-derived C(1) compounds.