The structural, electrical, and optical characteristics of nanometric Fe2O3-x films fabricated on <100> Si and SiO2 substrates by ablating an iron target with a KrF excimer laser in low pressure (0.05–1.0 Pa) O2 atmosphere are reported. The thickness of films fabricated with 4000 laser pulses is ∼80 nm for samples deposited at the lowest pressure (0.05 Pa) and decreases gradually to 50 nm at the highest used pressure (1.0 Pa). The film mean composition results close to FeO at lower pressures (0.05–0.10 Pa) and to Fe2O3 at higher pressures (0.5–1.0 Pa). From glazing incidence x-ray diffraction spectra, it was inferred that deposits are poorly crystallized, especially the ones prepared at relatively high oxygen pressures (0.5–1.0 Pa). Scanning electron microscopy inspections show that surfaces are plane and uniform, with very rare (<0.1 μm-2) submicron droplets. From x-ray reflectivity spectra, surface roughness results very low (0.1–0.5 nm, increasing with O2 pressure). The films present a semiconductor behavior, with electrical energy gaps increasing from 0.43 to 0.93 eV with increasing O2 pressure, while the optical energy gap varies from 1.60 eV (0.05 Pa) to 1.74 eV (1.0 Pa). Very high thermoelectromotive force coefficient values were measured (up to 1.65 mV/K). It is also shown that films present promising gas sensing properties.