We report on the atomic layer deposition (ALD) of MnO and NiO thin films on Si(1 0 0) using Mn(EtCp)2 [EtCp=ethylcyclopentadienyl, (C2H5)C5H4] and Ni(EtCp)2 in the temperature range of 150–300 °C. H2O or O3 is selected as oxygen source for the depositions. The growth temperature (Tg) and oxygen source impact on the structure, electronic density, and impurity concentration for the as-grown MnO and NiO films have been studied using X-ray reflectivity (XRR), grazing incidence X-ray diffraction (GIXRD), and Fourier transform infrared (FTIR) spectroscopy. A steady growth rate of 0.024–0.025 nm/cycle for the films grown using Mn(EtCp)2 and H2O was observed in the Tg range of 250–300 °C. FTIR does not show any carbon impurities in the MnO films grown with H2O. The films grown using Mn(EtCp)2 and O3 at 300 °C exhibit poor adhesion on Si(1 0 0). NiO films with low amounts of contaminants are …