Nucleosides were phosphorylated with different N-(O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2’, 3’. and 5’-isomers had been confirmed by comparison with authentic samples on the basis of HPLC analysis. The conversion percentage of nucleoside indicated that N- (O, O-diisopropyl) phosphoryl aspartic acid reacted with adenosine and guanosine at a much higher rate than other kinds of N- phosphoryl amino acids, while phosphorylation of cytidine and uridine was relatively easy by using N- (O.O- diisopropyl) phosphoryl threonine. The result could give some clue to the prebiotic code origin of nucleic acid and protein. Nucleosides were phosphorylated with different N- (O, O-diisopropyl) phosphoryl amino acids to give nucleoside mono phosphates in aqueous solution. 2 ’, 3’. And 5’-isomers had been confirmed by comparison with authentic samples on the basis of HPLC analysis. The conversion percentage of nucleoside indicated that N- (O, O-diisopropyl) phosphoryl aspartic acid reacted with adenosine and guanosine at a much higher rate than other kinds of N- phosphoryl amino acids, while phosphorylation of cytidine and uridine was relatively easy by using N- (OO-diisopropyl) phosphoryl threonine. The result could give some clue to the prebiotic code origin of nucleic acid and protein.