It is studied the thermal and radiation stability of the IR-detectors based on photosensitive films of solid solutions in PbS-CdS system obtained by chemical vapor deposition on a pyroceramics substrate. It is shown that the films exhibit a high stability in the composition and photoelectric properties when heated to 405-410 K at normal conditions and under the influence of irradiation y-radiation ~300 P/min with a set of the total dose up to 10 7 R. At increase of the CdS content in solid solution to the 17 mol. % "red" limit of the photoanswer moves in short-wave area to 1.6 microns, and a maximum photosensitivity - from 2.5 to 1.2 microns. Frequency of change rate of resistance at a light flare depending on structure of a film is in an interval from 10-100. According to the frequency characteristics photoresistors on their basis are most effective at 298 K for frequencies of the radiation modulation of 0.25-6.0 kHz. At temperature decrease of a sensitive layer to 253 K time constant increases no more, than twice at increase in volts-watt sensitivity by 6-8 times. For a sensitive element of 0.48x0.48 mm 2 on the basis of solid solution Cd 0 062Pb 0 938S the maximum value of detective ability at 300 K ( max, 1000 Hz) from a source like "A"made2.510 11 cm/(W-Hz 1/2).