Characterization of oxide and oxyhydroxide iron (Fe) and aluminum (Al) forms in highly-weathered Ultisols of the southeastern United States is necessary to develop further understanding of colloidal-facilitated transport of pollutants, sorption of contaminants, erosion, and soil genesis. The objective of this study was to examine Fe and Al oxides from several highly-weathered Ultisols and evaluate their relationships with particle size fractions and other soil chemical and physical properties. Samples contained in the argillic horizon of 13 highly-weathered pedons were examined. These pedons either contained kandic horizons, were in a kaolinitic mineralogical family, or were in a siliceous mineralogical family with a subactive cation exchange capacity activity (CEC) class. Standard characterization analyses were performed on all pedons. Samples were fractionated into a coarse (2 to 2000 μm) and fine (< 2 μm) fraction, and ammonium oxalate (Feo and Alo) and dithionite-citrate-bicarbonate (Fed and Ald) extr...