Adsorbates of [Fe(CN)5SCN]3- complex ions on semiconducting Pb(SCN)2 surfaces were subject to photoelectromotive force (PEMF) investigations. Laser flash excitation of the adsorbates at 560 nm yields a weak PEMF signal due to spectral sensitization of the semiconductor Pb(SCN)2, not absorbing in the visible region. PEMF signals observed with laser flash excitation at 337 nm are explained by hole trapping accompanied with photoinduced redox reactions of the complex, when the number of flashes is increased.