Group V substituted zeolites were characterized using periodic DFT. It is found that the group V sites in zeolite materials become more hydrophobic and less reducible descending the column of the Period Table. The stable site with T=O group for T = V, transforms into a site with T-OH group for T = Ta. For niobium both sites (Nb-OH and Nb=O) are in competition with each other. The presence of Lewis acid base pairs is predicted in Nb and Ta dehydrated zeolites. (C) 2010 Elsevier B. V. All rights reserved.