High-spin and low-spin Fe(III) porphyrins were studied by high resolution X-ray fluorescence and fluorescence-detected X-ray absorption spectroscopy using synchrotron radiation. The high-spin Kβ spectrum is split into a main peak (Kβ 1 , 3 ) and a satellite (Kβ ) at 15 eV lower energy. The low-spin Kβ 1 , 3 peak shifted 0.7 eV to lower energy, and the Kβ feature is almost unobservable. Ligand field multiplet calculations show that spin-up ( 5 A 1 ) and spin-down ( 7 A 1 ) states are separated for the high-spin spectrum. Spin polarization of the Kβ-detected absorption was demonstrated by enhancement or elimination of the 1s → 3d transition, depending on the Kβ region used for detection.