  The Fourier Imaging X-raySpectrometer (FIXS) is one of four instruments on SAC-0, the Argentinian satellite being proposed for launch by NASA on a Scout rocket in 0000/0. The FIXS is designed to provide solar flare images at X-ray energies between 0 and 00 keV. Observations will be made on arcsecond size scales and subsecond time scales of the processes that modify the electron spectrum and the thermal distribution in flaring magnetic structures