SOI-HITS is an ambitious, innovative and timely STREP project that will enable significant energy consumption savings and reduce waste in processes such as: combustion in domestic boilers; oil & gas storage and transportation; CO2 capture and sequestration. It aims to deliver at least 15% saving of energy consumption in domestic boiler industry (~40 million domestic boilers in the EU with a growth rate of 15% per year); equating to 3.6 billion Euros saved per year. For this ambitious goal, SOI-HITS will develop innovative CMOS-compatible, Silicon-on-Insulator (SOI) integrated smart microsensor systems, capable of multi-measurand (water vapour, temperature, gas, flow, UV/IR) detection under harsh environment conditions (to 225oC, high water vapour level). SOI technology has several advantages over bulk silicon: enhanced electro-thermal isolation giving lower power consumption, ease of forming arrays of MEMS membranes, option of tungsten as a high temperature CMOS metal, direct integration of high-performance temperature and UV optical solid-state sensors. The smart multisensor chip will comprise multiple micro-hotplates with tungsten micro-heaters onto which selective nanostructured and thin film metal oxide sensing layers have been deposited. For the gas sensors (CO2 (concentration 6-10%, CO (0-1000ppm), and H2S (0-100ppm)), we will achieve fast thermal response time of a few ms and loss per micro-hotplate below 0.2mW/oC. Water vapour sensors, flow sensors (for liquid & gas) and precision on-chip temperature controllers will be also integrated. On-chip processing electronics, including drive circuitry, filters, amplifiers, processing circuits and analogue to digital interfaces, operating at 225oC, will be developed. The extension of the SOI platform to optical detectors, such as UV photodiode flame detectors and IR combined sources/detectors, will be explored. Finally development of a High Temperature SIP (system in a package) will enable real-world demonstrators.