This paper presents a study of a Production and Storage Spar Platform concept design for operations in deep water, under the environmental conditions of the Campos Basin, Brazil. This study is the result of a research sponsored by Ageˆncia Nacional do Petro´leo – ANP. The theme was chosen due the good results obtained by this kind of platform in the North Sea and the Gulf of Mexico. Since the exploration of hydrocarbonets is moving to deeper waters, where the Spar concept seems to be one of the best options for the task, due to its simplicity in construction and operation. Although it looks simple, this work had required perceptive studies, and the best way chosen to carry it out, was dividing it in two directions: one dealing with the design method and naval architecture aspects and other with its hydrodynamic behavior. The first line took into consideration the hull generation, compartmentation, weight distribution and stability. A design methodology is presented and the interaction of these factors are showed, taking into account the hydrodynamic results. The second line has favored the evaluation and the control of the vertical motion, excited by dominant waves from the spectra of energy of the sea, and the horizontal motions due the low frequency excitations, and its interaction with the mooring system.