A hetero-trimetallic lanthanide-substituted bismuth titanate (BLT, where lanthanide is praseodymium) with stoichiometry Pr0.75Bi3.25 Ti3O12 has been obtained. as both highly homogenized crystalline and amorphous thin films using three different BLT precursors: (i) precursor A-(Pr(OC3H7i)(3), Bi(OOCCH3)(3), Ti(OC3H7i)(4)); (ii) precursor B-(Pr(OC3H7i)(2)(acac), Bi(OOCCH3)(3), Ti(OC3H71)(3) (acac)); and (iii) precursor C-(Pr(OC3H7i)(2)(acac), Bi(OOCCH3)(3), Ti(OC3H7i)(2)(acac))(2). These three BLT precursors (A, B, Q are prepared by reacting constituent monometallic precursors in the desired stoichiometry and by employing controlled acidic hydrolysis via the sol-gel method. Paramagnetic Pr(III), being a f(2) ion, gives characteristic 4f-4f transition bands (H-3(4) --> P-3(2), H-3(4) --> P-3(1), H-3(4) --> P-3(0), and H-3(4) --> D-1(2)) in the visible region, the intensities of which have been found to be highly sensitive to even minor changes in the immediate coordination around Pr(III), occurring as a result of the progress of polycondensation reactions of three multicomponent BLT sols. We have used the changes with time in the intensities (represented by oscillator strengths of these four 4f-4f bands) and the magnitude and variation of the spectral parameters evaluated from the observed spectra with a view toward monitoring the sol-gel reactions of BLT precursors A, B, and C. 4f-4f transition spectra of the aliquots, withdrawn from the hydrolyzing A, B, and C sols at different time intervals, represent the changes occurring in the Pr(III) environment with the progress of sol-gel hydrolysis of BLT, and are used to investigate the kinetic performance in hydrolysis of the three precursors. Kinetics of hydrolysis of precursors A, B, and C indicate that all four f-f transition bands of Pr are almost equally sensitive to precursor hydrolysis in the order A > B > C. (C) 2003 Elsevier Science (USA). All rights reserved.