The stability of n-Si vacuum-coated with metal-free phthalocyanine (H2Pc) and copper phthalocyanine (CuPc) was studied as a function of the light intensity and redox couple in aqueous solutions. Although the photocurrent at an n-Si coated with H2Pc or CuPc decayed slowly at low light intentsities (1 mW/cm1 2), photopassivation was rapid at higher light intensities (100 mW/cm2). The magnitude of photocurrent and the inhibition of photocorrosion depended upon the solution conditions. Addition of iodine, which is a dopant for the Pc layer, led to larger photoeffects and a lower rate of photopassivation, although the electrode was still unstable after longer irradiation times. Further improvement in stability was observed in the presence of the highly concentrated electrolyte, 11 M LiCl.