Selenium is a trace element and an essential micronutrient with a biogeochem-ical cycle involving soil, bedrock, water and the atmosphere. Emission of volatile organic selenium species such as dimethyl selenide (DMSe) or dimethyl diselenide (DMDSe) from marine systems has shown to contribute significantly to the atmospheric selenium budget. We investigate the atmospheric fate of volatile organic selenium in respect to their oxidative transformation using the Vocus 2R PTR-TOF-MS in controlled laboratory experiments. The goal of this research is to identify kinetics and chemical products of the reaction between these volatile organic selenium species and some important atmospheric oxidants such as ozone or hydroxy radicals. Additionally, we are interested in the physiochemical behavior of oxidized atmospheric selenium in the atmosphere. Using the Vocus’ aerosol inlet and by employing different chemical ionization methods such as proton transfer or ammonia cluster formation, we study the gas to particle partitioning behavior of oxidized selenium. Furthermore, we develop methods to allow for detection of ambient atmospheric selenium by bringing the portable Vocus 2R to field sides with known high selenium emissions.