The objective of RESPIRE is to carry out, from space, an exhaustive spectro-imaging survey of the sky in the wavelength range 1.6 - 6.5 microns, with a spectral resolution of 90 and a spatial resolution of 12 arcsec., within a period of four or more years. This spectral range, essentially opaque from the ground, is very rich in spectral features that trace the stellar populations and the interstellar medium in all its forms (molecular, atomic and ionised gas, PAHs, dust, ices). An excellent performance in detection will be achieved (500 and 10 microJy at 3 microns, in standard and long exposure modes, respectively) thanks to the passive cooling of the entire instrument to 60 - 80 K.