The photoelectrochemical properties of n-GaAs are studied in acidified chloride electrolytes of different compositions, with the objective of preventing its photocorrosion. After irradiation of a n-GaAs electrode, under fixed anodic potential, current−voltage curves (J−V) experience two modifications: a negative shift in the onset potential of the photocurrent, Vp, and a dark cathodic peak at ∼−0.38 V (saturated calomel electrode, SCE). During irradiation at +0.4 V (SCE) in an acidified chloride solution, the illumination current increased with time rather nonlinearly. In an electrolyte composed of 2.5 M H2SO4 and 6.0 M LiCl at +0.4 V (SCE) the illumination current reached a saturation value of 18 mA cm-2 after ∼40 min of irradiation. The relationship between the illumination current density and the square root of the irradiation time is linear; however, it has a changing slope at certain time. Therefore, according to the predictions of the diffusivity equation solution, the electrode reactions are limit...