Absorption cross sections of SO2 have been obtained in the 24 000-29 000 cm-1 spectral range (345-420 nm) with a Fourier transform spectrometer at a resolution of 2 cm-1. Pure SO2 samples were used and measurements were performed at room temperature (298 K) as well as at 318, 338 and 358 K. This is the first time that temperature effects in this spectral region are reported and investigated. This paper is the first of a series that will report on measurements of the absorption cross section of SO2 in the UV/visible region at a higher than previously reported resolution and that will investigate temperature effects in support of tropospheric, stratospheric and astrophysical or planetary applications. © 2009 Elsevier Ltd. All rights reserved.