Geochemistry is one of the main tools at the disposal of geoscientists to investigate sedimentary basins and petroleum systems. Major advances have been made over the last decade in the geochemical characterization of sediments, diagenesis and diagenetic processes, hydrocarbon source rocks, and petroleum systems. We are seeking contributions that focus on the application of geochemistry aiming to resolve some of the complex histories of the petroleum systems around the Atlantic conjugate margins.