Tm3+:Er3+:Yb3+ doped Y2SiO5 powders were prepared by combustion synthesis with estimated as-prepared weight (wt.) % concentrations of 0.25:0.0:2.0, 0.25:0.5:2.0 and 0.25:1.0:2.0, respectively. Blue (Tm3+: (1)G(4) --> H-3(6)), green (Er3+: S-4(3/2), H-2(11/2) --> I-4(15/2)) and red (Er3+: E-4(9/2) --> I-4(15/2)) upconversion (UC) emissions were observed under 975 nm infrared diode laser excitation. The UC process took place via energy transfer from Yb3+ to Er3+ and Tm3+ ions. The CIE chromaticity coordinates of Tm3+:Er3+:Yb3+ doped Y2SiO5 powders were investigated as a function of the diode laser power and Er3+ concentration. (C) 2010 Elsevier B.V. All rights reserved.