Laser created X-ray sources have been investigated both theoretically and experimentally using λ = 1.06 μm and λ = 0.26 μm and short pulses (0.5 nsec). Some preliminary results are given with UV radiation obtained with a long pulse (25 nsec) excimer laser. The con-version efficiency of the X-ray emission in the sub-keV (0.1-0.75 keV) and keV (0.75-2 keV) ranges is given for various atomic numbers and a large range of laser intensities. Using these results and resist sensitivities, we discuss the characteristics of the laser required for X-ray lithography.