SkyMed/Cosmo is a research project aimed to the realization of a space-borne observing system devoted to the monitoring of the Earth surface in the optical and microwave ranges. The project, which is supported by the Italian Space Agency, foresees the utilization of a group of satellites, each of which equipped with a set of instruments allowing different spatial resolutions. The entire system is realized for operational purposes over regional scale (i.e.: disaster monitoring, observation of marine and terrestrial ecosystems), that require a very short re-visitation time. The phenomena to be taken into account for the disaster monitoring are mainly earthquakes, landslides and marine emergencies. The SkyMed/Cosmo system promises to become a useful tool both for the analysis of risks and assessment of damages, and in any case where rapidly changing features (days or weeks) should to be observed. The system will be able to monitor the ground, marine and coastal environments, and to provide useful information about water circulation, water quality, sea bottom vegetation, soil coverage, geology, coastline monitoring, archaeology and cartography. Some of these applications, like those related to marine environment, will require a very high signal to noise ratio as well as accurate radiometric calibration. This work describes the outgoing feasibility study devoted to regional scale environmental applications of remote sensing by the SkyMed/Cosmo optical payload. The analysis of the SkyMed/Cosmo performance and diagnostic capabilities is given and discussed in comparison with those allowed by other satellite instruments.