X-ray photoelectron spectroscopy combined with first-principles simulations are used to determine the band alignments of ZrO2 thin films on silicon. Theoretical band offsets were calculated by simulating the ZrO2/Si interface by means of plane-wave pseudopotential calculations. Experimental band offsets were determined by measuring the core-level to valence-band maximum binding energy differences. Excellent agreement was obtained between the theoretical (3.5–3.9 eV) and experimental (3.65 eV) valence band offsets. Both theoretical and experimental analyses predict the conduction band offset to be ∼0.6–1.0 eV which indicates the intrinsic limitation of ZrO2 to be considered as a viable alternative gate dielectric.