Gelatinous compositions of matter which are useful as polymerization catalyst components and are highly stable in terms of OH-decay rate, as well as similarly stable solid compositions of matter formed from such gelatinous compositions, are described. The gelatinous and solid compositions are formed from hydroxyaluminoxane. Also disclosed is a process comprising converting a hydroxyaluminoxane into a gelatinous composition of matter, whereby the rate of OH-decay for the composition is reduced as compared to that of the hydroxyaluminoxane. Olefin polymerization processes and catalysts formed from these novel compositions of matter also are disclosed.