The characteristics of the fluorescence spectra of 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole (BDD) doped in Si-Ti binary oxides by the sol-gel method were investigated as a function of time in its transitions from sol to gel to xerogel. The intensity of the fluorescence spectrum decreases with the increase in the Ti content. A characteristic BDD excimer fluorescence was observed during the transition from gel to xerogel only in a mixture of tetraethyl orthosilicate (TEOS) and tetraisopropoxy titanium (TPOT) but not in pure TEOS, indicating that the presence of a tetrahedrally coordinated titanium ion species plays a significant role in the formation of the excimer. A possible model has been proposed for the entrapment process of BDD during the sol to gel to xerogel transitions.