The sol-gel preparation of the nanocrystalline nonsubstituted and Sr-substituted gadolinium aluminate was studied. The metal ions, generated by dissolving starting materials of metals in the diluted acetic acid were complexed by 1,2-ethanediol to obtain precursors for the non-substituted and Sr-substituted GAP. In the sol-gel processing different starting gadolinium materials such as gadolinium nitrate or gadolinium oxide were employed. The influence of the temperature and the amount of substituent on the phase purity of GAP was also investigated. Phase transformations, composition and micro-structural features in the gels and polycrystalline samples were studied by TA, XRD, IR spectroscopy and SEM.