When combined with Adaptive Optics, integral field spectroscopy, i.e. observation of a sky field simultaneously in a number of spectral passbands, is the most efficient way to perform spectro-imaging at high angular resolution. GriF will provide the CFHT community with such a capability in the near infrared K-band. This extension will be completed by means of two simple optical devices to be installed in the KIR cryostat (the infrared camera of PUEO): a cooled grism in the filter-wheel and a cold aperture on an entrance focal plane wheel. They will be completed by a room-temperature Fabry- Perot (FP) interferometer in front of KIR. The FP selects narrow bandpass images while the grism spatially separates them, giving a 3-D spectroscopic capacity within a compact and light design. At each exposure, several (up to 9) monochromatic images of a rectangular field of about 36 arcseconds X 4 arc-seconds will be simultaneously acquired, allowing a precise subtraction of continuum and background. The cooled grism will guarantee a low background environment, thus a good sensitivity at K. The medium spectral resolution (about 2600) will fit to a number of programs and will represent a considerable improvement on imaging with narrow- band filters. Thus, combining high angular resolution with the spectroscopic diagnosis, GriF will allow the study of a large class of compact objects or structures, especially in the extragalactic domain where its sensitivity should be unique.