In this study, we found that ammonium-functionalized polyhedral oligomeric silsesquioxanes (POSSs; 2Am-POSS and Am-POSS) with high proportions of cagelike decamer (T-10-POSS; 54% and 45%,. estimated from Si-29 NMR spectra) could be successfully prepared by the hydrolytic condensation of 3-(2-arninOethylamino)propyltrirnethoxysilane and 3amimopropyltrimethoxysilane, respectively, using trilluOromethanesulfonic acid as a catalyst in hydrophobic alcohols such as 1-hexanol. In addition, on the one hand, it was also found that 2Am-POSS, a mixture of cagelike octainer (T-8-POSS), T-10-POSS, and cagelike dodecamer (T-12-POSS), could be separated into T-8-POSS and a mixture of and T-52-POSSs- by exploiting,their different solubilities in 1-butanol. On the other hand, in the case of Am-POSS, T-8-POSS and a mixture.of T-10- and T-12-POSSs could be isolated by treatment with ethanol methanol mixed solvent and 1-propanol. The XRD patterns of cast films of T8POSS showed many sharp diffraction peaks, indicating crystalline structures, whereas those of T-10- and T-12-POSSs showed no diffraction peaks, indicating amorphous structures, for both the case of 2Arn-POSS and Am-POSS. These results suggest that the difference in crystallinities between the ammonium-functionalized T-8-POSS and T-12-POSSs causes their different solubilities in alcohol solvents.