A floating hydrocarbon processing/storage structure with a first and second assembly, each including a hull having side walls, one or more storage tanks and a deck structure, a connection structure interconnecting the hulls, processing equipment situated on the deck structures, at least one riser connected to a subsea hydrocarbon well and to the processing equipment and/or storage tanks, with a mooring system connecting the processing/storage structure to the sea bed, each hull including a hull deck structure bridging the side walls, the connection structure including a central deck extending at or near the height of the hull deck structures along at least 70% of the length of the hulls, the central deck supporting at least one of: risers vertically extending from the central deck between the hulls to the sea bed, fluid ducts horizontally supported on the central deck, and at least one drilling/work-over rig or crane.