A windowless gas target was developed for the production of secondary high-spin isomer beams (HSIB). An 16O target in the compound form of CO 2 gas was used to produce a 145 mSm beam by using an 16O( 136Xe, 7n) 145 mSm reaction. The target gas pressure was kept constant at 50 Torr. A target thickness of about 1 mg/cm 2 was achieved with a 10 cm target length. Gas was recirculated and the consumption was very little.