This fellowship project aims at the development of Dr. David Ehrenreich's young career, focusing on the atmospheric characterisation of exoplanets. More than 500 planets have been detected around other stars during the past 15 years. It is now time to go beyond the exoplanet census and start determining the physical and chemical properties of these new worlds, understanding how they formed, assessing their ability to host and sustain life, and eventually, detecting signs of life elsewhere in the Universe. These fundamental questions can be addressed by observations of exoplanetary atmospheres, supported by theoretical modelling. The objectives of the project are milestones leading to the detection of life: (i) detecting new worlds suited for atmospheric characterisation and (ii) pushing atmospheric characterisation of exoplanets toward the lowest-mass exoplanets, including hot neptunes and super-earths. These objectives will also serve the preparation of the detection and atmospheric characterisation of habitable, Earth-like exoplanets. To achieve these objectives, the applicant will work at the University of Geneva Observatory (UniGE), the leading actor in exoplanet detection aiming at becoming a European centre of expertise in exoplanets with a strong involvement in atmospheric characterisation of exoplanets. The fellow will get involved in the on-going planet search projects within the Harps and SuperWasp consortia. He will use his expertise in the atmospheric characterization of exoplanets to study the properties of the exoplanets detected at UniGE with space, ground-based, and archival spectroscopic data. He will participate to the implementation of projects that will enable the detection of numerous characterisable Neptune- to Earth-mass exoplanets: the ground-based transit survey NGTS (2013), the European PLATO space mission (2018), and the project of a mini-satellite dedicated at detecting and characterising exoplanets (2016).