CaTiO3 :Pr3+ shows strong red emission at 612 nm from D-1(2) to H-3(4) transition of Pr3+. Absorption by the 5d state lies in the long-wavelength side of the UV range. Co-doping with Bi3+ greatly enhanced UV excitation in the spectral range 370-390 nm in which GaInN light-emitting diodes may emit. Doping with 5% Bi and 5% Al, the maximum UV excitation peak moved to 370 nm, and the absorptions at 380 and 390 nm were increased to 90 and 75% of the maximum absorption, respectively. It was found that the S-1(0) --> P-3(1) absorption transition of Bi3+ was quite strong and spanned a UV spectral range similar to the d-bands of Pr3+. The enhancement of UV excitation is attributed to energy transfer from Bi3+ to Pr3+, and Bi3+ plays a role as a sensitizer. (C) 2003 The Electrochemical Society.