The abnormal photocurrent of the anodic film formed on lead in 4.5 mol dm(-3) H2SO4 at 1.4V (vs. Hg/Hg2SO4) for 1 h was investigated by several electrochemical methods. The experimental results show the abnormal photocurrent is due to a two-phase system in the film, i.e. a p-type semiconductor t-PbO and an n-type semiconductor PbO1.41. The composition of the two-phase system is about PbO1.19 when the photocurrent is zero.