We have designed, developed and constructed a CO2 laser based LIDAR-DIAL field tested with preliminary measurements of concentration of water vapor two. Two years we have developed this preliminary measurements using alternatively the R20 and R18 lines in the branch at 10 micron of two twin CO2 lasers and we have obtained the density profile on a long path of about 800 m. At present the maximum range of the lidar signal on the absorption line is limited by dynamic range and the NEP of our detector. To extend the range of lidar signals a theoretical work has been done about the use of new laser lines for range resolved measurements of water vapor for distance of 1 km. In fact the absorption coefficient of the on-line 10R20 is very strong and the lidar signal for range up to 1 km is obscured by noise of the detector. The theoretical work already gave a good results and presently we are making the experimental measurements to compare with the theoretical data.