Surface resistance measurements on Tl‐Ba‐Ca‐Cu‐O thick films (∼15 &mgr;m) magnetron sputtered onto BaF2‐buffered, silver‐based (Consil 995) substrates have been made at a microwave frequency of 22 GHz. The relatively large‐area films (∼5 cm2) are characterized by surface resistance values of 6.9±2 m&OHgr; at 11.3 K and 30.2±1 m&OHgr; at 77 K; the corresponding values for Cu are 10 and 22 m&OHgr;, respectively. These results demonstrate that Tl‐Ba‐Ca‐Cu‐O can be deposited ontolarge‐area,metallicsubstrates with characteristic surface resistance values lower than Cu at 4 K. Orientation of the film should improve the surface resistance at 77 K, thereby making the fabrication of microwave cavities that are superior to Cu possible.