The emergence of Service-Oriented Architecture (SOA) as an approach for integrating applications that expose services, presents many new challenges to organizations that ensure the decisional aspect of company by adopting the SOA like a support architecture. The proposed architecture will facilitate research and development of Decision-Making and decision support systems in SOA. This chapter describes Service Oriented Architecture with decisional aspect (SOAda) . To define a new set of concepts necessary for modeling the three views: business, information and decision, a new meta-model called Decisional Model of Service (DMoS) will be presented. Some of these concepts are already known, whereas others are new and are proposed as an element of this chapter. The architecture leading elements are: the DMoS meta-model and the new architecture SOAda. Finally, the proposed architecture will be illustrated with a case study in inventory management .