Semiconductor photoelectrochemistry (PEC) has great potentials in addressing the issue of worldwide energy shortage by converting solar energy into chemical fuels. However, semiconductor materials immersed in strong aqueous acidic and alkaline electrolytes are prone to (photo)corrosion reactions and display limited stability either at applied bias or under light illumination. Among them, technologically-important III-V semiconductors (InP, GaAs, GaP etc.) with superior photovoltaic performances suffer from such surface corrosion processes. Herein, we systematically investigate the surface corrosion chemistry of these materials directly at the semiconductor/electrolyte interfaces in both strong acid and base. Various dark/light and open-circuit/applied-bias conditions are studied and compared in order to fully reveal the chemical, electrochemical and photoelectrochemical stability of these III-V semiconductors. Techniques including inductively coupled plasma mass spectroscopy (ICP-MS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and atomic-force microscopy (AFM) are all employed to probe both the physical and chemical changes after their surface corrosion transformations. Combined with considerations of thermodynamic pourbaix diagrams, comprehensive understandings are gained over their diverse (photo)corrosion behaviors at different potentials. Eventually, rational strategies are devised to effectively protect these semiconductors from rapid corrosion while maintaining sustainable PEC performances for solar fuel production.