This study investigated the electrical and especially the magnetic properties of Niobium (Nb) doped TiO2 (TiO2 :Nb) thin films. Experiments evidently present that both minimum of ferromagnetism and resistivity exist in a same Nb doping ratio (3.0%). The XPS experiments revealed that Nb doping simultaneously increases and compensates for oxygen vacancies. The proposed model explains magnetic and electrical properties by analyzing oxygen vacancies induced by vacuum annealing or by Nb doping. (C) 2014 Elsevier B.V. All rights reserved.