The target of these "JournŽes" is to draw up the state of art concerning sources, detectors, characterisation and imaging techniques in the terahertz domain, located at the frontiers of infrared optics and microwaves, and also to focus on the numerous emergent applications of these new "T" rays. This conference is sponsored by the CNRS (National Centre for Scientific Research) and the SFO (French Optical Society). The french version of the leaflet of the conference announcement can be download here [pdf file (474 Ko)].