The relationship was examined between soil moisture tension expressed as soil water potential (pF) and microdiffusion of oxygen (ODR) values. Homogenized samples from various horizons of Eutric Fluvisol and Eutric Histosolwere investigated at 4 pF values (1.5; 2.2; 2.7; 3.2) using the classical Richard method. Oxygen diffusion rate (ODR) was measured in soil samples at these pF values according to theLemon and Ericksson method (1952),modified byMalicki and Walczak (1983), using platinum and reference electrodes. The highest values of ODR ranging from 59.3 to 74.9 μg O₂m⁻²s⁻¹ were formed at pF 2.2 forEutric Fluvisol.Meanwhile, the maximum values of ODR forEutric Histosolranged from 86.4 to 108.1 μg O₂m⁻²s⁻¹ at the pF 3.2 were estimated. The lowest values for ODR for bothEutric Histosol and Eutric Fluvisolwere found at pF 1.5.