CuxS layers on polycaproamide, obtained by the adsorption-diffusionmethod, have been studied. These layers are formed when the ions of pentathionate (K2S5O6) sorbed into polycaproamide react with a solution of copper(I) salt. By X-ray diffraction studies it was determined that the CuxS layers obtained are of three phases, comprising covellite (CuS), geerite (Cu1.6S), anilite (Cu1.75S) and chalcocite (Cu2S). The concentration ratio of the phases depends on the period of polycaproamide sulfuration in a potassium pentathionate solution. Chalcocite prevails in the composition of CuxS film on PKA. The films were characterized by means of IR spectroscopy. IR absorption spectra were investigated in the region of the wavenumbers 200-1400 cm-1. The characteristic absorption maxima were found in the regions 242-243, 268-290, 339-384, 422-463, 538, 611-612, 879-929, 1018-1095, 1186-1224 cm-1 and assigned, respectively, to delta(S-S-S) and ni (Cu-S), gamma r(SO3), ni(S-S) and ni(Cu-S), delta as(O-S-O), delta s(O-S-O), ni (Cu-S), ni s(S-O) and ni as(S-O). Measurements of electrode potentials in CuSO4 solutions of different concentration have shown that the response time and stability of electrodes in Cu2+ ion solutions depend on the phase composition. Electrodes composed from Cu1.75S and Cu1.6S are not stable in CuSO4 solutions. The response time of a Cu2S electrode depends on concentration change. The change of the potential with an active Cu2+ ion concentration is linear in the range of 1.10-3-4.10-2mol_dm-3, the slope of the linear portion being 31.5mVper decade. The obtained experimental values have been compared with the theoretical values calculated on the basis of thermodynamic data.