The BELCOLOUR project brings together Belgian teams to form an expert group for optical remote sensing of coastal waters. The objective of the project is to improve the theoretical basis and software tools for applications of suspended matter and chlorophyll-based products in coastal waters. Existing products will be improved by theoretical advances and by use of new sensors, product quality will be assessed and future applications will be prepared. The target products are suspended matter and chlorophyll concentration maps for coastal waters and derived higher level products. The target region is Belgian coastal waters but the methodology is generic and exportable. The primary target user group is coastal zone environmental managers though further potential user groups have been identified and will be developed as products become more reliable and more cost-effective. The project tasks are divided into the following work packages: Theory: Theoretical studies will focus on critical areas including aerosol correction, air-sea interface correction, bio-optical model inversion in high tripton/CDOM water and product error analysis. Measurements: Calibration measurements will focus on the chlorophyll-specific phytoplankton absorption and the suspended matter-specific backscatter. Seaborne experiments will be dedicated to improving specific algorithm components. Measurements from the AERONET sunphotometer and from the Belgian water quality monitoring programme will be further exploited. Image processing: Satellite imagery from a range of satellite and airborne optical sensors will be processed using a generic approach. User interaction: End-user needs will guide the development of higher level products and the design of future satellite-based systems. Dissemination: Results will be published in peer-reviewed articles and via Internet. International actions: Belgian experts will join/form international groups. Responsibility of the partners is divided thematically as follows: ULB (Phytoplankton, inherent bio-optical properties), VITO (airborne), and MUMM (theory, satellite remote sensing).