Semiconductor photoelectrochemistry (PEC) has great potentials in supplying the worldwide energy demands via production of hydrogen/hydrocarbon fuels using sunlight. However, semiconductor materials are prone to (photo)corrosion reactions in contact with strong aqueous acidic and alkaline electrolytes and display limited stability when flowing currents through the electrodes 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 probe the surface corrosion chemistry of these materials occurring at the semiconductor/electrolyte interfaces in strong acidic and alkaline media. Various dark/light and open-circuit/applied-bias conditions are studied and compared to fully reveal the chemical, electrochemical and photoelectrochemical stability of these III-V semiconductors. Experimental techniques including inductively coupled plasma mass spectroscopy (ICP-MS), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and atomic-force microscopy (AFM) are employed to probe both the physical and chemical changes after their surface corrosion transformations. Combined with considerations of thermodynamic pourbaix diagrams, comprehensive understandings of their diverse (photo)corrosion behaviors are gained over different potential regions. Eventually, protection strategies are rationally devised to inhibit rapid materials corrosion and enable these semiconductors for sustainable solar fuel production.