Measurements of reflectivity of water and ice at 100 GHz, 140 GHz, and 180 GHz are reported. Measurements on water covered the temperature range 0¿C to 50¿C. No anomalies in the dielectric properties of water due to the presence of either salts or organic matter were found. The reflectivity of water and its temperature dependence are consistent with recent dielectric property models derived from data at other wavelenghts. The index of refraction of fresh ice is constant at 1.78 throughout this region.