In this paper, crack-free and transparent Gd0.9La0.1VO4 single-crystal co-doped with Yb3+ and Ho3+ ions has been grown by Czochralski method. The absorption and emission spectra of the crystal were measured at room temperature. With the absorption spectrum, the intensity parameters Q;, of Ho 31 ions were fitted based on Judd-Ofelt theory, which are Omega(2) = 7.87 x 10(-20) cm(2), Omega(4) = 7.41 X 10(-20) cm(2) and Omega(6) = 1.99 X 10(-20) cm(2). The spectral parameters of Ho3+ ions were also calculated. The emission spectrum of Gd0.9La0.1VO4 crystal co-doped with Yb3+ and Ho3+ ions was detected when the sample was excited by LD at 980 nm and the intense up-conversion emissions were observed at 550, 660 and 750 nm. (c) 2005 Elsevier B.V. All rights reserved.