Cytosine and uracil, which are components of RNA molecules, were obtained from complex organic matter produced by quenching a CO-N-2-H2O high-temperature plasma. The carbon yields of cytosine and uracil were 0.01% and 0.08%, respectively, which were almost as much as those of amino acids. It was understood that processes of high activation and rapid quenching, which may be found in meteoritic impact or lightning, are important for the formation of bioorganic compounds from the CO-N-2-H2O gas mixture.