This paper describes a ground-based Raman lidar for the measurement of vertical concentration profiles of tropospheric water vapor. The system will also be used to assess the feasibility of carbon dioxide profile determination. The main components are a xenon chloride excimer laser, reflective 0.4-m transmitter and 0.8-m receiver optics, liquid edge filter for suppression of the Rayleigh and Mie scattered photons, and an echelle grating polychromator for wavelength separation. The data acquisition is done by a fast multichannel scaler. The apparatus is described, and first moisture measurements up to a vertical distance of 3 km taken in less than 2 minutes with a spatial resolution of 120 m are presented.