The adsorption affinity of soil minerals for phosphate depends on the molecular coordination of the surface species. Previous research using Fourier-transform infrared (FTIR) spectroscopy suggested that phosphate sorption on iron oxides may be as either monodentate or bidentate surface complexes. Our research objective was to more definitively determine the coordination mode of phosphate on poorly-crystalline iron oxides. Moist samples of ferrihydrite or goethite containing between 25 and 1200 mmol/kg of adsorbed phosphate at pH 6, or 900 mmol P/kg between pH 4 and 8 were analyzed using extended x-ray absorption fine structure (EXAFS) spectroscopy. Phosphorus K-EXAFS data were collected on Beamline X-15B at the National Synchrotron Light Source, Brookhaven National Laboratory. This beamline has a focused beam and employs a solid-state Ge detector to isolate the phosphorus fluorescence signal. EXAFS spectra indicated the presence of second-shell Fe(III) in the P coordination environment, confirming the dominance of inner-sphere surface complexes as has been proposed from FTIR and XANES analyses reported by others. EXAFS fitting analysis to determine inter-atomic P-Fe distances as an indicator of coordination mode will be discussed. Problems with collecting P K-EXAFS spectra in high-Fe samples will also be discussed. Insights on phosphate bonding mode are useful for predicting the potential dissolution and mobility of phosphate bound to soil iron oxides.