Abstract: The composition and state of silver-electroplated deposits exposed to light of different wavelengths have been investigated using XPS and AES. The results showed: ( 1 )The phototarnishing effects of different wavelengths had the following order: 1537 A>3650 A>sunlight. ( 2 )For the same wavelength, the longer the exposure time, the more serious the phototarnishing. ( 3 )Auger parameter measurement showed that Ag2O amounted to 42.9% of the total silver after exposure for 18 hours to 2537 A ultraviolet light, and 17.6% for 24 hours. ( 4 )XPS measurement showed that the surface of the silver deposit was first oxidized and chloridized when exposed to light in the atmosphere, and the silver chloride might then be transformed into Ag2O, which was eventually reduced in ultraviolet light into black superfine silver particles and AgO. After immersing a silver deposit in a Na2S solution, the part of the deposit reexposed to air above the Na2S solution became blue in colour, while remainder part still immersed in the Na2S solution was not tarnished. From the binding energy of Ag(3d) and S(2p) and from M4 VV and M5VV Auger lines, it could be deduced that the non-tarnished silver deposit was still metallic, while the blue coloration was due to Ag2S. Thus, the tarnishing reaction in air of the silver deposit after immersion in the Na2S solution may be written as follows. 4Ag + O2 + 2H2O + 2Na2S→2Ag2S + 4NaOH