Unexpectedly large photocurrents arising at polycrystalline silver electrodes, during cathodic reduction of carbon dioxide dissolved in various aqueous salt solutions, are reported. The quantum yields of the photocurrent are shown to be strongly affected by the surface roughness, reaching almost 1% at the photon energy of 3.5 eV. The sharp peak of the photocurrent observed at this photon energy suggests that surface plasmons on silver play the main role in the observed photoeffect.