X-ray absorption spectroscopic studies at the Fe K-edge have been performed for iron oxychloride, FeOCl, and its alkoxy substituents, FeOCl1-x(OR)(x), where R is CH3 or C2H5. By comparison with the X-ray absorption near edge structure (XANES) spectra for some references such as gamma-FeOOH, Fe3O4, and Fe(acac)(3), it was confirmed that the iron octahedra become regular as the amount of substitution increases, even though the valence state of the iron remains unchanged by substitution reaction. Detailed information on crystal structure, including bond angles as well as bond distances, was obtained from multiple scattering extended X-ray absorption fine structure (EXAFS) analyses of FeOCl and its methoxy substituent over long range up to similar to 6 Angstrom. We utilized a minimal set of adjustable parameters (only five interatomic distances and the associated Delta E(0), and Debye-Waller factors), letting geometry do the rest of the work for them. The resultant structure for the methoxy substituent showed that the local symmetry around the iron becomes higher than that for FeOCl and also is very similar to that for gamma-FeOOH as expected from the XANES spectra. One-dimensional electron-density map along the c-axis was obtained in two different ways; one was from X-ray diffraction intensities and the other from EXAFS fitting results. The two one-dimensional electron-density maps were in good agreement, which reflects the reliability of the EXAFS fit. This EXAFS analytical method could be effectively applied to various two-dimensional systems with very poor crystallinity.