The CO+(A2 Pi to X2 Sigma +) and CO2+(A2 Pi u to X2 Pi g) fluorescence produced by impacting CO and CO2 with synchrotron radiation of wavelength in the 175-750 AA region was investigated and the production cross sections were measured. For primary photon wavelengths longer than 630 AA, the fluorescence cross sections show structure at the positions of the Rydberg series for both gases. For primary photon wavelengths shorter than 500 AA, the cross sections decrease monotonically with the wavelengths. The present measurements are compared with the various results reported by previous authors.