<p>Passive remote sensing of atmospheric carbon dioxide uses spectroscopic measurements of sunlight back-scattered by the Earth's surface and atmosphere. The current state-of-the-art retrieval methods use three different spectral bands, the oxygen A band at 0.76 μm and the weak and strong CO<sub>2</sub> absorption bands at 1.61 and 2.06 μm, respectively, to infer information on light scattering and the carbon dioxide column-averaged dry-air mole fraction XCO<sub>2</sub>. In this study, we propose a one-band XCO<sub>2</sub> retrieval technique which uses only the 2.06 μm band measurements from the OCO-2 satellite. We examine the data quality by comparing the OCO-2 XCO<sub>2</sub> with collocated ground based measurements from the Total Carbon Column Observing Network (TCCON). Over land and ocean the OCO-2 one-band retrieval shows differences to TCCON observations with a standard deviation of ~ 1.30 ppm and a station-to-station variability of ~ 0.50 ppm. Moreover, we compare one-band and three-band retrievals over Europe,the Middle East and Africa region and see high correlation between the two retrievals with a SD of 0.93 ppm. Compared to the three-band retrievals, using only the 2.06 μm band similar XCO<sub>2</sub> retrieval accuracy and precision can be obtained while retaining a similar data yield.</p>