A method for producing a gas comprising at least 80 vol % carbon monoxide from a Fischer-Tropsch off-gas comprises: (1) feeding Fischer-Tropsch off-gas through a column comprising an adsorbent bed at high pressure and discharging effluent; (2) reducing the pressure in the column and the bed slightly; (3) rinsing the column and the adsorbent bed with methane or a mixture of methane and carbon dioxide; (4) reducing the pressure of the column and adsorbent bed to a low pressure; (5) rinsing the column and adsorbent bed with a mixture of hydrogen and nitrogen; (6) pressurizing the column and adsorbent bed to a high pressure using a mixture of hydrogen and nitrogen. The product stream obtained in step (3) comprising at least 80 vol % carbon monoxide can be sent as feed to a Fischer-Tropsch reaction. In an embodiment, a gas comprising at least 80 vol % hydrogen is also produced.