The stability and acid base properties of group V Al containing zeolites have been investigated using a combination of experiment and theory. Using periodic density functional theory for a systematic investigation on a series of model zeolites, it is shown that the XdO group is more stabilized for X = vanadium and X OH for X = niobium or tantalum. The relative stability trend between both types of groups is found to be similar to the one observed in group V containing pure silica zeolites. The position of the group V element in the framework is also discussed. The use of protonation and deprotonation energy has enabled rationalization of the higher basicity of Nb Al containing zeolite on the molecular level.