Microspherical hydrochar was synthesized by hydrothermal carbonization of trehalose. In contrast to other saccharide precursors, this results in a distinctly binary sphere diameter distribution with monodisperse small spheres and polydispers large spheres. Pyrolytic post-carbonization converted the oxygen-rich polymer structure to a nanocrystalline hard carbon structure. The binary size-distribution and large BET surface area make this material highly promising for applications in catalysis, filtration, and energy storage devices.