The Cape Verde Atmospheric Observatory (CVAO) is part of a bilateral German-UK initiative to undertake long-term ground- and ocean-based observations in the tropical Eastern North Atlantic Ocean region. The CVAO exists to advance understanding of climatically-significant interactions between the atmosphere and ocean and to provide a regional focal point and long-term data context for field campaigns. Measurements of O3, CO, NO, NO2, NOy and volatile organic compounds (VOCs) began at the site in October 2006. Chemical characterisation of aerosol measurements and flask sampling of greenhouse gases began in November 2006, halocarbon measurements in May 2007, and physical measurements of aerosol in June 2008. On-line measurements of greenhouse gases began in October 2008.The CVAO is a World Meteorological Organisation-Global Atmospheric Watch (WMO-GAW) global station and quality-assured atmospheric data for use by the international scientific community are regularly deposited at both the WMO-GAW and British Atmospheric Data Centre (BADC) data archives.