A mechanism of the alpha-beta structural phase transition (SPT) in V2O5 is proposed. The driving force of the SPT is suggested to be the U-5 shear strain transforming the orthorhombic unit cell of the alpha-phase into the monoclinic unit cell of the beta-phase. According to the model, the SPT is characterized by a concerted displacement of V2O5 chains and is of martensitic type. Results of periodic DFT calculations performed for structures along the transformation path corroborate the proposed mechanism. The calculated height of the energy barrier is in a good agreement with the heat of transition determined experimentally for the inverse beta-alpha transformation. Possible ways of the experimental verification of the proposed mechanism are discussed. (C) 2013 Elsevier Ltd. All rights reserved.