The radiance of the lunar surface in the 8.0 to 10.4 μ region of the infrared spectrum was measured as a function of wavelength with a resolution better than 0.2 μ. Measurements were taken from a high altitude station (elevation 11,500 feet) to minimize the corrections required for atmospheric absorption. The radiance values obtained after correction are not compatible with gray or blackbody radiation at any temperature. Emissivities calculated on the basis of a 120°C lunar surface temperature vary from near unity at 8.5 μ to 0.90–0.93 in the region from 10.0 to 10.4 μ.