A new precursor combination, hafnium tetraiodide and oxygen for atomic layer deposition of hafnium oxide thin films has been studied. The growth rate of hafnium oxide on Si(1 0 0) substrates was investigated at substrate temperatures ranging from 400 to 750 degreesC. A saturation of the growth rate with increasing substrate temperature depended on the oxygen pressure and was achieved at 500-620 degreesC. Growth of phase pure polycrystalline monoclinic HfO2 could be realised by tuning process parameters such as the partial pressure of O-2 and the evaporation temperature of HfI4. Straightforward thickness control was demonstrated by varying the number of deposition cycles between 50 and 1000.