This paper presents the design of the Mexilha˜o-1 Platform (PMXL-1), located at Brazilian Santos Basin, focusing in the concept development and design of the light weight optimized jacket. PXML-1 is a gas and condensate production hub platform with 525 MMscf/d processing capacity and 18350 metric tons (mton) topside design load. Installed in 172m water depth, is the deepest fixed production unit in Brazil. Jacket concept was developed aiming to structural and functional optimization, based on previous company work on Campos Basin. Due to height, top and base dimensions and expected weight, lift option was discarded and a 4-leg launched and self upended jacket was selected. To increase structural efficiency, bracing was provided by fewer but larger diameter and heavier walled members. Launch trusses, with conventional bay spans, form a central core that is used also to support risers, I-tubes and other appurtenances. Face bays are double spanned, X-braced, with central cross nodes stabilized by members connected to the central core. Horizontal levels have no peripheral members and are double X-braced. Top horizontal frame level is located above operational wave crest, reducing environmental loads, and bottom level is elevated about 6m from mudline. Topside modules are directly supported by jacket main legs and two additional dummy legs, eliminating a module support frame. Foundation is provided by eight large diameter vertical skirt piles. Comparison with PNA-2, a conventional 8-leg platform, installed about 20 years ago in Campos Basin, in similar environmental conditions, with analogous functional requirements, shows considerable advantages and savings. In comparison to PNA-2, PMXL-1 jacket weight is reduced by 32% and pile weight is reduced by 65%. Number of structural elements and tubular connections to be fabricated and erected is also drastically reduced.