The molecular structure of precursors in sol-gel processing of PbTiO3 is modified via β-diketone substitution for the isopropyl groups of titanium isopropoxide. Crystallite size and crystallization behavior are studied using x-ray diffractometry and differential thermal analysis. The crystallite size decreases with increasing amount of β-diketone substitution. Whereas the weight percent of crystalline phase first decreases and then increases with increasing β-diketone substitution. Our results indicate that the β-diketone substitution reduces the size of the structural units in the gel network resulting in smaller crystallite size and more nucleation sites in the powders produced.