Gels in the system BaO-Al2O3-SiO2 have been prepared from metal alkoxides and barium acetate. The processes during calcination and crystallization as a function of composition have been followed by means of DTA, TGA, IR and XRD. Three major regions of accelerated weight loss have been observed which correspond to the evaporation of physically adsorbed species, the oxidation of -Al(OOCCH3) and the oxidation of Ba(OOCCH3)(2). The latter reactions are accompanied by strong exothermic DTA signals. The oxidation products of barium acetate tend to foam and to block the paths and channels for the oxygen supply and the removal of the volatile oxidation products, inhibiting a complete oxidation. Thus, the combustion of Ba(OOCCH3)(2) is strongly dependent on the concentration, the sample volume and the heating conditions. IR shows that the gels heated up to 800 degrees C are structurally similar to glasses of the same composition. In all gels the metastable crystallization of hexacelsian is strongly preferred to the stable monoclinic celsian. DTA crystallization peaks appear between 960 and 1080 degrees C, depending on composition. In most samples hexacelsian is the only phase present, even after 5 h isothermal heat treatment.