The extraordinary Hall effect was studied in 1 to 10nm thick nickel films prepared by radio-frequency diode sputtering (plasma) and electron-beam evaporation of Ni. The Hall resistance, R(H), does not reach saturation in fields up to 0.5 Tin films that are not uniform while for uniform films, R(H) saturates at 0.3 T. The films prepared by plasma sputtering showed a jump-like behavior of the extraordinary Hall coefficient, R(S), that is due to the presence of two phases tetragonal (nonmagnetic) and face-centered cubic(fcc) (magnetic)-in the initial growth stage and subsequent phase transition of the tetragonal lattice to fcc at a film thickness of about 4 nm around which the extraordinary Hall coefficient R(S) increases abruptly reaching its maximum. The films prepared by electron-beam evaporation consist only of the fcc phase and have a dome-like R(S) dependence on film thickness. (c) 2011 Elsevier B.V. All rights reserved.