This study examines the thermal dehydration of beta-maltose monohydrate into the anhydride, in which a liquid phase formation during the reaction process has significant influence on the mechanistic and kinetic features of the overall reaction. The thermal dehydration proceeds by a surface reaction and subsequent reaction interface shrinkage model, with the characteristic formation of a glassy product layer. On heating the sample linearly, the glass transition of the surface product layer occurs at approximately 370-380 K, producing a crystalline monohydrate-supercooled liquid anhydride with a core-shell structure. Under the self-generated conditions, the thermal dehydration is controlled by the diffusion of the produced water vapor via the surface liquid layer, which is hindered by the enhanced cohesion of reacting particles. Finally, the reacting particle assemblage forms a dome at approximately 403 K, and the thermal dehydration is impeded by the as-produced thick surface layer.