We report on ultrasound measurements in a single crystal of the antiferromagnet U2Rh2Sn as a function of temperature and magnetic field. We find pronounced anomalies in the sound velocity at the Néel temperature, 25 K, and at the field-induced spin-flop-like transition at 22.5 T, which points to a strong magnetoelastic coupling. Additionally, we find that in the paramagnetic regime the temperature dependence of the magnetic susceptibility and the field dependences of the magnetization and sound velocity of transverse acoustic waves can be well described assuming a localized character of the 5f electrons. Using this premise, the crystal-electric-field scheme of U2Rh2Sn has been determined.