Dimethylsulphide (DMS) gas phase oxidation with OH radicals was investigated by long path FT-IR spectroscopy and by ion chromatography (IC) and HPLC-MS 2 to quantify the reaction products and evaluate heterogeneous processes. The experiments were performed considering two different NO x (NO 2 +NO) levels. The initial concentration of NO 2 was varied from 24 ppbV (NO x =1 ppmV) to 953 ppbV (NO x =10 ppmV). Photolysis of H 2 O 2 was used as the OH-radical source. SO 2 , dimethylsulphoxide (DMSO), dimethylsulphone (DMSO 2 ), methanesulphonic acid (MSA), methanesulphinic acid (MSIA) and methane sulphonyl peroxynitrate (MSPN) were identified as the main sulphur-containing products. The results indicate that higher NO x levels play a significant role in the chemistry of CH 3 S(O) x radical, influencing both the SO 2 /MSPN ratio and the amount of the sulphur species in the condensed phase, and that the NO 2 /NO ratio could influence the trends in the molar yields of the different products. For this reason the NO x content results a limiting parameter when on measure DMS in atmospheric environment.