The adsorption of CO2 on hematite α-Fe2O3(012) has been investigated in ultra-high vacuum (UHV) using temperature-programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS). CO₂ adsorption on this surface exhibits complex behavior, resulting in multiple desorption features in TPD. For coverages up to one molecule per unit cell (0.5 molecules per Fe2+ cation), two desorption features centered around 150 K and 220 K increase concurrently with increasing coverage. IRAS shows that this behavior originates from a thermally activated conversion of weakly bound, physisorbed CO2 into surface carbonate (CO32-) species at temperatures above 100 K, a process that directly competes with molecular desorption. By supplying CO₂ at temperatures just below the carbonate desorption temperature, higher carbonate coverages can be obtained. These findings contribute to our understanding of CO2 activation on Fe2O3(012) and will be a prerequisite for surface reaction studies.