Limb sounding of mesospheric water vapor using pure rotational emission in the long-wavelength infrared region has been demonstrated using data from the ELC-1 rocket experiment, launched in October, 1983. By simultaneously analyzing H2O emission at 23--29 &mgr;m and CO2 emission in the &ngr;2 band region, effects due to uncertainties in the atmospheric temperature and instrument calibration are minimized. The H2O profile obtained from ELC-1 is consistent with other fall to early-winter measurements. Given accurate line-of-sight pointing information, this approach will be feasible for global mesospheric H2O sounding from limb-viewing satellites. ¿ American Geophysical Union 1993