This document describes the requirements and specifications of the enviroGRIDS BSC-OS Portal. It concerns mainly with user, functional, technological, and usability requirements of user applications. The functionality and data repositories required in Web and Grid infrastructures are analyzed together with the main issues of the interoperability between functional modules as well as between the geospatial and Grid infrastructures. The document explores the possible architectural and technological solutions, and details and recommends solutions for the development of the BSC-OS portal.