The structures and stabilities of the titanium analogues of fully condensed silsesquioxanes, [HTiO1.5]n, n = 4−12, are investigated with ab initio electronic structure theory including electron correlation effects. In addition, the distribution of Ti atoms in T8, H8TipSi8-pO12; p = 1−7, are compared with the Al distribution in zeolites. The fully substituted POSS are found to have similar structures to the silicon analogues though the titanium compounds seem to be more stable for all cage sizes than the silicon compounds.