This work aims to present the VULCAIN mission study to design and characterize a new CubeSat mission for Earth Observation dedicated to volcanoes. The project is supervised by the European Space Agency (ESA) and involves six Italian partners. The project involves the construction of two 12U nanosatellites flying in formation. Each satellite embarks two instruments onboard: a COTS VIS-NIR camera and a multispectral thermal camera with four channels in the 8-12 mu m spectral range. The main scientific objectives are to measure the Land Surface Temperature (LST) and to combine VIS-TIR data to enhance the observation on volcanic areas by adding morphological analysis.