Interaction of hydrogen with aluminum phosphide clusters has been investigated using the density functional method of Becke's three-parameter hybrid functional with the nonlocal correlation of Lee, Yang, and Parr. Berny structural optimization and frequency analyses are performed with the basis of 6-311 + G(d). Our results show large binding energies of a single hydrogen atom on small Alp clusters and large highest occupied and lowest unoccupied molecular-orbital gaps for (AIP)H and (AIP)(5)H making these species behave like magic clusters. Calculations on two hydrogen atoms on AIP clusters show large binding energies for (AIP)(n)H-2 with n = 1, 3, 5, and 7. In general the binding energy of H and 2H are both found to decrease with an increase in the cluster size. And the calculations also suggest that hydrogen should be dissociated on (AIP)(2) and (AIP)(3). (C) 2009 Elsevier B.V. All rights reserved.