The Atmospheric Chemistry Studies in the Oceanic Environment (ACSOE) programme was a 5-year NERC Community Research programme to investigate the physico-chemical processes occurring in the layer of atmosphere immediately above the oceans. It was developed from 1996 to 2000. The programme comprised a wide range of species and aerosol measurements coupled with integrated modelling studies. Measurements were made from April 1996 to December 1998.