A rotating gas cell has been developed as a target for charged-particle beams to produce monoenergetic neutrons via the reactions 1H(t,n), 2H(d,n), 2H(t,n), 3H(p,n), and 3H(d,n). An intense monoenergetic neutron source results when this cell is equipped with a rugged entrance foil and pressurized to 1 MPa, and when a prolific source reaction such as 1H(t,n) is chosen. Neutron flux levels of typically 4 × 109 cm-2 ·s-1 between En = 8 and 12 MeV are being used to measure activation cross sections.