The Heliophysics Integrated Observatory, HELIO,will deploy a new Europe-wide distributed network of services that will address the needs of a broad community of researchers in heliophysics.This new research field explores the "Sun-Solar System Connection" and requires the joint exploitation of solar, heliospheric, magnetospheric and ionospheric observations. HELIO will provide the most comprehensive integrated information system in this domain; it will coordinate access to the distributed resources needed by the community, and will provide access to services to mine and analyse the data.HELIO is designed around a Service-oriented Architecture. The initial infrastructure will include services based on metadata and data servers deployed by the European Grid of Solar Observations (EGSO; IST-2001-32409).We will extend these to address observations from all the disciplines of heliophysics; differences in the way the domains describe and handle the data will be resolved using semantic mapping techniques.Processing and storage services will allow the user to explore the data and create the products that meet stringent standards of interoperability.These capabilities will be orchestrated with the data and metadata services using the Taverna workflow tool.HELIO will address the challenges following the I3 activities model:Networking – we will cooperate closely with the community to define new standards for heliophysics and the required capabilities of the HELIO system;Service – we will integrate the services developed by the project and other groups to produce an infrastructure that can easily be extended to satisfy the growing needs of the community;Joint Research – we will develop search tools that span disciplinary boundaries and explore new types of user-friendly interfacesHELIO will be a key component of a worldwide effort to integrate heliophysics data and will coordinate closely with international organizations to exploit synergies with complementary domains.