In-beam spectroscopic investigations of 109Sn have been performed using the reactions 55Mn(58Ni, 3pn) and 106Cd(α, n) with E58Ni = 240 MeV and Eα = 23 MeV, respectively. An extended level scheme of 109Sn is presented showing high-spin states up to Ex ≈ 8 MeV with Jπ = (41/2+). The problem of the 109Sn ground state has been solved identifying a 12.8 keV transition deexciting the 7/2+ state to the 5/2+ g.s. A half-life of T½ = 7(1) ns has been measured for the 17/2+ state at Ex = 2114 keV. The experimental data are compared with the predictions of shell-model calculations.