Due to its excellent physico-chemical properties, silicon carbide (SiC) has been recognized for its potential as a structural material in nuclear reactor applications. One of the remaining issues that can limit usability of this material is corrosion. In this talk, I will discuss our recent theoretical studies revealing corrosion mechanisms of SiC exposed to the hydrothermal water environment. I will first discuss, from the thermodynamic point of view, the open question of which corrosion products form, i.e., the formation of SiO2 vs Si(OH)4. Secondly, I will discuss the elementary interfacial reactions driving corrosion, including a discovery of the unexpected hydrogen scission reaction that plays a key role in surface degradation. Our kinetic studies reveal that SiC is dissolved directly into the water without forming the silica layer, although the reactions are analogous to those observed during dissolution of silica. Finally, I will discuss the surface orientation effect on SiC corrosion.