[en] γ-spectra from the (n,n'γ) reaction of 2.75 MeV neutrons of natural Tl and enriched ²⁰³Tl were measured with Ge(Li) detectors. By means of these measurements about 120 γ-lines could be assigned to either of the two isotopes. About half of the lines - however accounting for more than 80% of the total γ-intensity - could be incorporated into the respective decay schemes, which could be extended in this way. Additionally, for a number of levels already known more accurate level energies could be determined. Comparison of the results with Hauser-Feshbach calculations leads to discrepancies which cannot be removed completely by variation of the model parameters within acceptable limits. (orig.)