Managing the water status of soil for crop production and waste disposal requires knowledge of the oxygen avilability in the profile. In this study a Captina silt loam (Typic Fragiudult) was nearly saturated and allowed to dry by drainage and evaporation. We measured oxygen flux and soil water tension simultaneously on two bare plots during three drying cycles. At the end of the study, we took undisturbed cores at three depth intervals in two plots and determined aeration porosity characteristics. The functional relationships between oxygen flux and aeration porosity determined from tensiometer data in the field and between tension and aeration porosity determined from the undisturbed cores were used to derive the mathematical relation between oxygen flux and soil water tension for the Captina profile.For the Captina soil, aeration porosity increased linearly with the natural logarithm of soil water tension. Similarly, the natural logarithm of oxygen flux was linearly related to aeration porosity. The combined equation describing oxygen flux as a function of soil water tension in the Captina soil constituted a power function. The description of the field data by the derived equations was excellent at all depths, and we found close agreement between the derived and the regression parameters of the power function relating oxygen flux and soil water tension.