The sol-gel synthesis of zirconia from zirconium n-propoxide in n-propanol can be controlled via the chemical modification of the alkoxide with acetylacetone. Hydrolysis is performed by aqueous solution of paratoluene sulfonic acid. Depending on the respective hydrolysis and complexation ratios different products can be obtained ranging from precipitates to sols. Stable non-aggregated colloids, about 2nm in diameter, can be obtained after aging the sols at 60-degrees-C. They are made up of small crystalline particles of tetragonal zirconia. Complexing ligands such as acetylacetone appear to prevent both condensation and aggregation processes.