We have performed spin-polarized first-principles calculations to explore the vanadium adsorption and diffusion on the AlN(0001)-(2 × 2) surface. The calculations were performed using the generalized gradient approximation with ultrasoft pseudopotential within the density functional theory. The surface is modeled using the repeated slabs approach. To study the most favorable reconstruction with vanadium adatom, we considered H3, T4, and T1 high-symmetry sites. We found that the most energetically favorable structure corresponds to the V-T4 reconstruction or the vanadium adatom located at the hcp-hollow (T4) site whereas the vanadium adsorption on-top of a aluminium atom (T1 position) is energetically unfavorable. The vanadium diffusion on surface shows an activation energy of 0.262 eV (T4–H3). The resultant reconstruction of the vanadium adsorption on AlN(0001)-(2 ×2) surface presents a lateral relaxation of some hundredth of Å in the most stable site. The comparison between the density of states of the AlN(0001) clean surface and with vanadium adatom is also examined. © 2012 Wiley Periodicals, Inc.