AbstractThis work reports the first rotational bands observed in the neutron-deficient nucleus $^{231}$ 231 U. Excited states were populated in the $^{232}$ 232 Th($α $ α ,5n) reaction at a beam energy of 52 MeV. Coincident decay $γ $ γ -rays were measured with the high-purity germanium detectors of the afrodite spectrometer array, in conjunction with a recoil detector to discriminate against the fission background. The bands are interpreted as the ground-state band $ν [633]5/2^{+}$ ν [ 633 ] 5 / 2 + , yrast band $ν [752]5/2^{-}$ ν [ 752 ] 5 / 2 - , and an excited band $ν [631]3/2^{+}$ ν [ 631 ] 3 / 2 + . Configuration assignments are supported by Cranked Shell Model and B(M1)/B(E2) calculations. The excitation energy of the $ν [752]5/2^{-}$ ν [ 752 ] 5 / 2 - bandhead is suggested to be 113.0 keV.