The Internet-based Electronic Commerce environment for interrelations among companies, known as B2B, is very complex. In order to operate in it, a tool is required to provide an integrated view of the diverse elements that interact in this business environment, facilitate its comprehension and support decision taking and the elaboration of strategies that add value to the companies that make transactions there. The need for this tool has lead to the creation of a generic model of the interrelations among companies and institutions in the B2B environment, which is the object of the present work. Among the different types of organizations that coexist in this environment, one can mention those that intermediate transactions between consumers and providers of goods and services – e-marketplaces –, companies that provide services related to technology, marketing, the legal area, the financial area, and those specialized in logistics and transportation. Partnerships with service providers allow companies to be responsible only for the attributions directly related to their business area, becoming able to adapt more quickly and easily to the frequent changes and to cope with the uncertainties of this virtual environment. In the elaboration of the B2B Global Model, concepts extracted from System, Network, Virtual Corporation and Supply Chain Theories were employed. Using System Theory, our purpose was to view the organizations acting in the B2B environment as parts in a system and not as isolated elements, because some of their properties can only be adequately treated if they are studied holistically. The B2B environment was also analyzed as a complex network whose components mutually support one another in order to cope with the growing technological requirements and the need to develop and adapt offers to the increasingly specific demands of this market. The theories dealing with Virtual Corporations and Supply Chains have contributed to a better understanding of the concepts related to Virtual Markets and to the product flow from the provider to the final consumer in this new business environment. As practical applications of the model, we present the analysis of Petrobras’ Customer Channel, one of the largest B2B portals in the world considering the volume of transactions, and a study of real options in companies oriented to B2B supported by this model. In the case of the Customer Channel, we show the model’s relevance in the understanding and characterization of the relationship among the entities that interact in this business environment. Checkland’s Soft methodology was employed to understand the problem situation and to formulate proposals for desirable and culturally feasible projects that are able to add value to the current version of the Customer Channel. The results of this application demonstrate the adherence of this model to reality, its contribution in the understanding of a complex real case and the determination of strategies to add value to the company.