8-Bromo-AMP and 8-bromo-GMP, which are key intermediate for the synthesis of 8-substituted purine nucleotides, were synthesized directly from AMP and GMP by the bromination with bromine-water in buffer solution. 8-Bromo-MP's were converted to 8-oxy compounds by the reaction with sodium acetate in acetic anhydride or in acetic acid. 8-Dimethylamino-GMP was obtained by replacement of 8-bromo-atom with dimethylamine. These 8-substituted purine nucleoside monophosphates were derived to 5'-diphosphates via phosphoromorpholidate. A convenient synthesis of [α-³²P]-8-bromo-ADP was described.