A novel series of benzenesulfonamides that contain ferrocenyl or ruthenocenyl moieties were synthesized and investigated for their ability to inhibit the enzymatic activity of physiologically relevant carbonic anhydrase (CA) isozymes: hCA I, II and tumour-associated IX (h=human). This manuscript describes the regioselective synthesis of both the 1,4- and 1,5-disubstituted-1,2,3-triazole benzenesulfonamides from ethynylmetallocene substrates. This is the first report describing the covalent attachment of organometallic moieties to the arylsulfonamide (ArSO(2)NH(2)) CA recognition pharmacophore. At hCA I these metallocene derivatives were either nanomolar or low micromolar inhibitors, while against hCA II and IX inhibition in the range of 9.7-80nM and 10.3-85nM, respectively, was observed. The ruthenocenyl derivatives gave superior CA inhibition compared to the ferrocenyl compounds across all three CA isozymes. These compounds constitute a new organometallic class of CA inhibitors with promising biological activity.