Photoelectric characteristics of isotype n-n-heterostructure PbS/ZnSe grown by low-temperature (T-s=540 K) MBE technique of lead sulfide thin films on monocrystalline ZnSe wafers are studied. Detailed examination of observed photoresponse and photoluminescence in wavelength range 0.4divided by4.8 flm under temperatures 77divided by300 K has demonstrated that the space charge region localized at the interface plays main part in the photo-properties of the structure.