EChO2013 is an open workshop about the EChO (Exoplanet Characterisation Observatory) M3 mission candidate to be held at ESA-ESTEC in Noordwijk (the Netherlands) on July 1-3, 2013. EChO is a mission dedicated to the observation of atmospheres of planets around nearby stars. These planets will span a range of masses, from gas giants to super-Earths, stellar companions and temperatures, from hot to habitable. EChO will investigate their composition and chemical/physical properties through repeated, simultaneous, multi-wavelength spectroscopic observations. This international workshop will provide an overview of the EChO mission and an opportunity for discussion and feedback in advance of the ESA Cosmic Vision review process. The ESA study and science teams will present the science case, mission objectives and concept, with invited talks by Industry and the Instrument Consortium on the mission and instrument designs respectively. Contributions from the Community covering all aspects of EChO, including science, targets, data processing and instrument design/critical technologies are welcomed. Time will be set aside for dedicated poster sessions and discussion.