The Global Mercury Observation System (GMOS) Project includes a specific Work Package aimed at developing tools (i.e. databases, catalogs, services) to collect GMOS datasets, harvest mercury databases, and offer services like search, view, and download spatial datasets from the GMOS portal (www.gmos.eu). The system will be developed under the framework of the Infrastructure for Spatial Information in the European Community (INSPIRE) Directive and the Directive 2003/4/EC on public access to environmental information, which both aim to make relevant, harmonized, high-quality geographic information available to support the formulation, implementation, monitoring, and evaluation of policies and activities that have a direct or indirect impact on the environment. Three databases have been proposed (on emissions, field data and model results), and each will be equipped with state-of-the-art, open-source software to allow for the highest performance possible. Web-based user-interfaces and prototype applications will be developed to demonstrate the potential of blending different datasets from different servers for environmental assessment studies. Several services (i.e. catalog browsers, WMS and WCS services, web GIS services) will be developed to facilitate data integration, data re-use, and data exchange within and beyond the GMOS project. Different types of measurement and model datasets provided by project partners and other sources will be integrated into PostgreSQL-PostGIS, harmonized by creating INSPIRE-compliant metadata and made available to a larger community of stakeholders, policy makers, scientists, and NGOs (as well as to other public and private institutions, as dictated by the Directive 2003/4/EC). Since interoperability is a central concept for the Global Earth Observation System of Systems (GEOSS), the Global Monitoring for Environmental and Security (GMES) and the INSPIRE Directive, guidelines developed in these three frameworks will be adopted. The use of standards will be a key concern throughout the encoding process. We will use the international standards for data and spatial schemas (ISO19107, ISO14825), for metadata (ISO19115:2003, ISO/DTS19139:2005, ISO15836) and for services (WMS 1.1.1, WFS 1.0, SLD 1.0, GML 3.1). On the other side, we will use XML for data exchange, together with SOAP, XSD, J2EE (for applications development) and W3C (for standard interfaces). With specific reference to GMES, the global database on mercury monitoring and the GMOS model outputs will be made available through a series of monitoring, forecast and re-analysis services. Finally, we hope the GMOS operational services will contribute to the Monitoring Atmospheric Composition and Climate (MACC) project, by providing access to atmospheric environmental services.