This study disserts about the costs of oil offloading in the exploration and production operation - E and P - of Petrobras in Campos` Basin. The development of the subject is based on the way the operation is performed, as much for shuttle tankers as for sub-sea pipelines; depicting the way costs were treated along the operation, aligned with the organizations structures involved in the offloading process. The core objective of this work is to offer a methodology to calculate the total offloading operation cost value, assigning each developed operation with its related cost components, using an Activity-Based Costing - ABC - approach. This approach considers that activities should be determined through the analysis of all stages. Once all activities are outlined, related cost components are assigned to each activity, calculating total oil offloading cost. It is not a target of this study to compare modals, though costs for volume of transferred oil, for pipelines and ships are presented at the end of the study. Sometimes, the choice for investments in one or another transport modal, might be based on intangible variables, or strategic decisions, contemplated on the Petrobras Strategic Plan. The expectation, at the end of this study, is to give the reader an understanding of the offloading costs and the contribution that the Activity Based Costing approach provides to calculate these costs for future projects evaluations.