NASA's Marshall Space Flight Center is designing, developing, and fabricating a Solar X-ray Imager (SXI) that will fly aboard a Geostationary Operational Environmental Satellite. The objective of the SXI is to obtain near real-time reconstruction of solar images from the sun in the spectral range of 6 to 60 angstroms. The SXI is being designed with the spatial resolution, sensitivity, and dynamic range sufficient to allow reconstruction of solar flares, loops, and coronal holes. To meet these design requirements the SXI utilizes a single Zerodur mirror element with a detector assembly that consists of a Galileo microchannel intensifier with a fiber optic coupler attached to a Charge Coupler Device. This paper summarizes the key design features of the SXI detector system and the challenges that are being faced in the development of the SXI detector assembly.