We present preliminary results of X-ray measurements on two small format compound semiconductor arrays. The devices, a 5 X 5 gallium arsenide array and a 3 X 3 cadmium zinc telluride array, were produced specifically to address the material, electronic and technological problems that need to be solved in order to develop mega-pixel, Fano limited spectroscopic arrays. The GaAs device was fabricated on 40 micrometer epitaxial material and has a pixel size of 200 X 200 microns2 with pitch 250 micrometer. The CdZnTe array was fabricated on a 5 X 5 X 1.6 mm 3 single crystal of spectroscopic quality. The pixel sizes were 350 X 350 microns2 with a pixel pitch of 250 micrometer. Measurements from 5.9 keV to 100 keV were carried out both in our laboratory and at the HASYLAB synchrotron research facility in Hamburg, Germany. The typical FWHM energy resolutions recorded at 5.9 keV by the GaAs and CdZnTe arrays were 394 eV and 900 eV, respectively.