The radiative lifetime of the 3s(2)3p(4) S-1(0) metastable state of Ar2+ was measured using an electrostatic ion beam trap. The lifetime was obtained by measuring the number of photons emitted during the S-1(0) -> P-3(1) magnetic dipole transition of Ar2+ as a function of the storage time. The wavelength of the photons was 311 nm. To correct for the collision-induced loss of Ar2+ ions in the trap, the storage lifetime of the Ar2+ beam was measured simultaneously by detecting Ar neutrals escaping from the trap. The obtained radiative lifetime was 157 +/- 19 ms, which was comparable to previously reported theoretical and experimental values. (C) 2017 Elsevier B.V. All rights reserved.