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 FREETEX (Free Troposphere Experiment) campaigns as part of ACSOE-OXICOA were carried to collect data. The dataset includes measurements of ozone (O3, NOx, NOy, HNO3, PAN, CO, HO2 + RO2, HCHO, VOCs, etc.), at the Jungfraujoch High Alpine Research Station (3,580m above sea level) over a five-week period in 1996 and again in 1998.