The phosphorylation of disaccharides by inorganic cyclo-triphosphate (P_3m) with a six-membered ring was examined in aqueous solution. In the phosphorylation of cellobiose, lactose, and α,α-trehalose with P_3m, β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl 1-triphosphate, β-D-galactopyranosyl-(1→4)-β-D-glucopyranosyl 1-triphosphate, and 3-O-triphospho-α-D-glucopyranosyl-(1→1)-α-D-glucopyranoside were synthesized with maximum yields of 28%, 35%, and 20%, respectively. In the reactions of maltose and sucrose with P_3m, two phosphorylated products were obtained in yields of 42% and 58%, respectively. The main phosphorylated products were assigned to α-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl 1-triphosphate and β-D-fructofuranosyl-(2→1)-2-O-triphospho-α-D-glucopyranoside by heteronuclear multiple bond correlation (HMBC) NMR. The phosphorylation mechanism of disaccharides with P_3m is discussed.