The photoluminescence and the excitation spectra of Bi3+ in the pyrochlore Y2Sn2O7 have been investigated in the temperature range of 15-300 K. The photoluminescence spectrum of Bi3+ in Y2Sn2O7 consists of two bands, one in the ultraviolet (385 nm) and the other in the visible (515 nm) part of the spectrum. The ultraviolet emission is attributed to the P-3(0.1) --> S-1(0) transition of isolated Bi3+ ions and the visible luminescence to Bi3+ pairs (clusters) in the host lattice. A comparative study of the Bi3+ luminescence in the pyrochlores Y2Sn2O7, La2Zr2O7 and Gd2GaSbO7 is presented. (C) 2002 Elsevier Science Ltd. All rights reserved.