Experiments were carried out to explore the effect of light on Au, Pt and Cu surfaces immersed in water, in order to study the changes of work function arising from the interaction between the metallic surfaces and water. The results show an action of liquid water about three times larger than that of low-temperature ice. Theoretical calculations, present in literature, have predicted values much lower than those we measured. The substantial changes in work function measured here appear to arise from the complex structure of water in the vicinity of the metal surface.