Upconversion fluorescence properties of a new Er3+/Yb3+-codoped lead oxyfluorosilicate glass under 975 nm excitation are investigated. The blue, intense green and red emissions centered at 408, 529, 545, and 667 nm, corresponding to the H-2(9/2) --> I-4(15/2), H-2(11/2) --> I-4(15/2), S-4(3/2) --> I-4(15/2), and F-4(9/2) --> I-1(15/2) transitions of Er3+, respectively, were simultaneously observed at room temperature. The important role of Yb2O3 in upconversion intensity is observed, and the influence of Yb2O3 and PbF2 on blue, green and red emissions is compared and discussed. The dependence of upconversion intensities on excitation power and possible upconversion mechanisms are evaluated. (C) 2004 Elsevier B.V. All rights reserved.