The electronic structure of transition-metal oxides is a key component responsible for material's optical and chemical properties. Specifically for metal-oxide structures, the crystal-field interaction determines the shape, strength, and occupancy of electronic orbitals. Consequently, the crystal-field splitting and resulting unoccupied state populations can be foreseen as modeling factors of the photochemical activity. Herein, we study the formation of crystal-field effects during thermal oxidation of titanium in an ambient atmosphere and range of temperatures. The X-ray absorption spectroscopy is employed for quantitative analysis of average t2g-eg crystal-field splitting (Δoct) and relative t2g/eg bands occupancy. The obtained result shows that Δoct changes as a function of temperature from 1.97 eV for a passive oxide layer created on a Ti metal surface at room temperature to 2.41 eV at 600 °C when the material changes into the TiO2 rutile phase. On the basis of XAS data analysis, we show that the Δoct values determined from L2 and L3 absorption edges are equal, indicating that the 2p1/2 and 2p3/2 core holes screen the t2g and eg electronic states in a similar manner.