A theoretical study on geometrical, thermodynamic and electronic properties of VxOy+ and VxOy (x = 2-4, y = 2-10) systems in different electronic states has been carried out. Analytical gradient techniques with a hybrid spin unrestricted and spin restricted Hartree-Fock density functional method (B3LYP) have been used. An analysis of potential energy surfaces at ground and some excited states renders the most stable structures an their corresponding vibrational frequencies. The reaction energies of the possible decomposition channels are reported and the results indicate that the formation of larger clusters is energetically favorable from the smaller VO+ ((3)Sigma), VO ((4)Sigma), VO2 (2A(1)), VO3 ((2)A'),V2O4 ((3)A ") and V2O5 ((1)A') systems and O-2 ((3)Sigma (g)). A comparative discussion of the bonding in these species has been carried out on the basis of the topological analysis of the electron localization function. Numerical results are analyzed and confronted with available experimental data.