Hydrogen cyanide, formaldehyde, and ammonia are considered important intermediates in amino acid synthesis by electric discharge. In this study, however, amino acid precursors were synthesized from aCO–N2mixture free of hydrogen atoms. An amorphous film composed of carbon, nitrogen, and oxygen was given from a highly activated plasma. When exposed to atmospheric moisture, this film incorporated hydrogen atoms to yield amino acid. This is a mechanism for amino acid synthesis without involving hydrogen cyanide, formaldehyde, and ammonia. ©1998 American Institute of Physics.