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 t(2g)-e(g) crystal-field splitting (Delta oct) and relative t(2g)/e(g) bands occupancy. The obtained result shows that Delta oct 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 degrees C when the material changes into the TiO2 rutile phase. On the basis of XAS data analysis, we show that the Delta oct values determined from L-2 and L-3 absorption edges are equal, indicating that the 2P(1/2) and 2p(3/2) core holes screen the t(2g) and e(g) electronic states in a similar manner.