The influence of hydrolysis on the hydrolytic polycondensation of aluminium alkoxides was studied. Two mechanisms of hydrolysis which give two different products are proposed for this process. Structural transformations of the resultant condensates, i.e. boehmite, (gamma-AlOOH), the product of hot-water hydrolysis, and gibbsite Al (OH)3, the product of cold water hydrolysis, have been investigated in temperature range 20-1300-degrees-C. An explanation was offered for the variations in the alpha-Al2O3 transformations of the condensate produced by room temperature hydrolysis.