Аннотация:The spectral mode of the infrared camera-spectrograph ASTRONIRCAM is characterized. Resolving power with the narrowest slit 0.9'' varies within R=1140-1440, wavelength calibration is stable at 0.3A level. The resulting instrument light efficiency in the long-slit mode ranges from 6 to 15% in the bands Y to K, scattering and diffraction efficiency of the surface-ruled grisms are primary limiting factors. The cross-dispersion mode throughput is ~4-5 times lower. Airglow lines and thermal background allow for exposures more than one hour long.