X‐ray emission from the 2s→ 1stransition in hydrogenic ions stimulated by an optical laser is proposed as a means of achieving lasing action in the x‐ray region. A net gain of 0.27 cm−1is calculated for the 18.97‐Å 2s→ 1stransition of O+7at an inverted population density of 1015ions/cm3in the presence of a Nd laser field of 5 × 108W/cm2.