Inspired by the CO2-reductatse activity of tungsten-dependent formate dehydrogenases (W-FDHs), a reduced W-FDH model, [W-IV(OH)(S2C2Ph2)(2)](-), was prepared in situ through hydrolysis of [W-IV(OPh)-(S2C2Ph2)(2)](-) (1) and its reactivity with CO2 was investigated. The reaction between [W-IV(OH)-(S2C2Ph2)(2)](-) and CO2 at room temperature leads to the formation of [WIV(O)(S2C2Ph2)(2)](2-) (2), which slowly oxidizes to [WV(O)(S2C2Ph2)(2)](-) (3). Isotopic labeling experiments reveal that the O atom in CO2 incorporates into 3. This implies that there is carbonic anhydrase like activity, in which carbonation and decarboxylation are mediated by a bis(dithiolene)tungsten complex.