The Atmospheric Chemistry Studies in the Oceanic Environment (ACSOE) was a 5-year Natural Environment Research Council (NERC) programme on tropospheric chemistry coordinated by the University of East Anglia and involving research groups from a number of UK universities and research institutes. The project had three consortia of UK institutes and universities, each of which focused on a different scientific topic. OXICOA (OXIdising Capacity of the Ocean Atmosphere) was a study of oxidant, radical and related gas-phase chemistry in the clean and moderately polluted marine atmosphere. The Testing Atmospheric Chemistry in Anticyclone (TACIA) project as part of the ACSOE-OXICOA program was carried to collect data. The dataset was collected by the C-130 research aircraft; a former transport aircraft operated by the Meteorological Research Flight (MRF), and includes in situ trace gas photochemistry measurements.