Among the carbohydrates used in compressed tablets, mannitol is the only one which possesses high heat stability. This substance melts at 167°, but does not decompose at temperatures up to 250°. Mannitol, alone and in combination with other carbohydrates, was fused and recrystallized or spray-congealed. Phase diagrams determined for these mixtures indicated that mannitol is eutectic with other carbohydrates. Selected drugs were soluble in the fused mixtures, and the crystallized or spray-congealed material obtained from these solutions possessed excellent flow and compression characteristics.