This work proposes a physically-based definition for the threshold voltage, V-TH, of junctionless nanowire transistors and a methodology to extract it. The V-TH is defined as the point of equal magnitude for the drift and diffusion components of the drain current. The methodology for V-TH extraction uses the device trans-conductance over drain current ratio characteristics. An analytical model for the threshold voltage based on the same definition has also been developed. Both V-TH extraction method and model have been validated through 3D simulations and have been applied to experimental devices. The proposed method has shown to provide a correct dependence on the temperature, while the double derivative of the drain current method overestimates this variation. (C) 2013 Elsevier Ltd. All rights reserved.