Abstract
In-beam γ-ray spectroscopic studies of superdeformed bands in the mass 190 region are discussed with emphasis on recent results for Tl nuclei. Among those results, superdeformation at the edge of the region (in (189)Tl) and the first measurement of a superdeformed quadrupole moment in an odd-Z nucleus ((191)Tl) is presented. The experiments were conducted with the Gammasphere array at the Lawrence Berkeley National Laboratory. They are examples for the type of physics addressed in the first phase of Gammasphere operation.