In the present work some nanostructured quaternary chalcogenides of the As-S-Sb-Te system have been investigated by a photoelectric method. The spectral distribution of steady-state photocurrent I_ph=(λ) and the relaxation curves of photocurrent I_ph=(t) were registered at positive and negative polarity of the applied voltage to the top Al illuminated electrode. In the spectral distribution of steady-state photocurrent, for the amorphous thin films As_1.17S_2.7Sb_0.83Te_0.40, As_1.04S_2.4Sb_0.96Te_0.60, As_0.63S_2.7Sb_1.37Te_0.30, and As_0.56S_2.4Sb_1.44Te_0.60 in the wavelength range λ=0.50÷0.92 mm (2.48÷1.35 eV) some maxima were detected, which are the result of the presence of binary clusters As₂S₃, Sb₂S₃ and Sb₂S₃. The photo-voltaic method was used to obtain the value of the band gap width, which was about E_g =1.41 eV.