A tunable amplification around 3600 A˚ has been demonstrated at low temperatures in the low‐energy side of the emission band of CaO crystals doped with F+centers. The pumping power was delivered by a pulsed nitrogen laser and the optical gain was measured in a coaxial configuration. The observed amplification fits the equations of the pumping cycle for this system reasonably well. The possibility of designing a tunable laser using this material is discussed in light of our experiments.