The phosphorylation reaction by inorganic cyclo-triphosphate (P 3 m ) having a six-membered ring was examined for d-aldohexoses and d-aldopentoses in aqueous solution. Similar to the process for d-glucose, d-galactose, d-xylose or d-allose were phosphorylated with P 3 m to give stereoselectively β-d-galactopyranosyl 1-triphosphate, β-d-xylopyranosyl 1-triphosphate or β-d-allopyranosyl 1-triphosphate with maximum yields of 31.3, 32.5 or 32.1%, respectively. On the other hand, in the reaction of d-ribose, d-lyxose, d-mannose or d-arabinose with P 3 m , the yields of β-d-ribopyranosyl 1-triphosphate, α-d-lyxopyranosyl 1-triphosphate, α-d-mannopyranosyl 1-triphosphate or α-d-arabinopyranosyl 1-triphosphate were 8.0, 16.5, 9.6 or 14.1%, respectively. The phosphorylation mechanism of d-aldopyranoses with P 3 m was also discussed.