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. The Aerosol Characterisation Experiment (ACE) aim was to determine and understand the properties and controlling factors of aerosol in the anthropogenically modified atmosphere of the North Atlantic, and to assess their relevance to radiative forcing. The data was collected as part of the HILLCLOUD-96 and 98 experiments, where a hill cap cloud which forms over a ridge on the north east of the island of Tenerife was used as a natural flow through reactor. The dataset contains the size distribution, size dependent chemical composition and hygroscopic properties of the marine and modified continental aerosol arriving at the North coast of the island.