The m—s and p—n-photodetectors based on GaAs, GaP, Si are widely employed in medicine, industry, security systems, etc. The detailed study of the temperature dependencies of the quantum efficiency of photoelectric conversion process at different photon energies has been reported for m-s-photodetectors based on GaAs and GaP, and p—n-photodetectors based on GaAs and Si. For photon energies less then and close to the band gap of the corresponding semiconductor the temperature dependencies of the quantum efficiency are similar for the all researched detectors. The quаntum efficiency increases with increasing temperature bеcause of the decreasing the width of the band gap and increasing the light absorption coefficient. For detected photon energies above the band gap the temperature dependencies of the quantum efficiency are practically temperature independent for the p—n-detectors based on GaAs and Si. The change in the quantum efficiency for the GaAs and Si detectors is less than 0,01 % per degree. For m—s-photodetectors based on GaAs and GaP the quantum efficiency increases with increasing temperature and tends towards saturation at high temperatures (300—400 K) and high photon energies (4—6 eV). We propose that this difference is connected with imperfections that always take place in the surface region of a semiconductor. For m—s-photodetectors the photoelectrically active region is near to the surface and imperfections influence on photoelectric conversion process. In p—n-photodetectors the photoelectrically active region is deep in the crystal and imperfections don’t influence on photoelectric conversion process. Thus, the p—n-photodetectors exhibit higher temperature stability then m-s-photodetectors have; in the same time m—s-photodetectors exhibit a higher photosensitive in the short-wavelength region.