SCHeMA is a multi-disciplinary collaborative project aiming to provide an open and modular sensing solution for in situ high resolution mapping of a range of anthropogenic and natural chemical compounds. Key targets are chemicals that may adversely affect marine ecosystems, living resources and ultimately human health. The SCHeMa tools will enhance ocean observing system capabilities to evaluate the impact of these compounds on marine water quality trends, thereby allowing one to rapidly localise problems and alert targeted groups.To achieve this, SCHeMA will develop: 1) chemical solid state miniaturized sensors functionalized using innovative analytical procedures to insure reliable and selective electrochemical and optical measurements of inorganic (micro-)nutrients/pollutants, VOCs, biotoxins, HABs, species relevant to the carbon cycle, as well as effective minimisation of chemical and physical interferences; 2) micro- and mini-analytical and mechanical fluidic systems; 3) miniaturized multichannel probes, incorporating the new sensors and fluidic systems, based on advanced hardware, firmware and wired/wireless interfaces allowing their plug-and-play integration to moored or free floating devices; 4) ad-hoc ICT solutions allowing remote control of data transfer and mapping system reconfiguration according to the OGC standard; 5) Web-based data information system for data storage, standardization, modelling and user-friendly accessibility by public authorities, scientists and existing observation/monitoring systems.The SCHeMA sensing tools will be optimised throughout their development via short field tests and inter-comparison with data obtained using established laboratory techniques. Long-term field applications in estuary and coastal systems will also be performed to (i) evaluate their ruggedness and reliability for high resolution spatial and temporal monitoring, and (ii) define their suitability for different applications and commercial production.