Reactions of the NO₃ radical with volatile organic compounds in the troposphere are discussed, based on results obtained by laboratory studies. It is found that the reactions with the biogenic species isoprene and dimethylsulphide, emitted in large quantities from vegetation and from marine phytoplankton respectively, may have important consequences for the overall chemistry and the radiative balance of the troposphere. Laboratory studies, applying FTIR spectroscopy as the main analytical technique, have shown that the main products of the reaction between isoprene and NO₃ in air are nitroxy-carbonyl-species. Such organic nitrates were also found as products of the reaction of NO₃ with other unsaturated aliphatic hydrocarbons. The organic nitrates are expected to liberate NO₂, by their degradation in the troposphere, thus serving as a ‘reservoir’ of this species which has a key role in tropospheric chemistry. The reaction of DMS with NO₃ in air is found to lead to production of methanesulphonic acid and SO₂ as the main sulphur-containing products. Both of these products will contribute to the formation of aerosols in the marine troposphere which, in turn, have an impact on the formation of clouds and thus on climate.