A series of solid-solution crystals GdxY1-xCa4O(BO3)3 (GdxY1-xCOB) (x = 0-1) were grown by the Czochralski (CZ) method. The distribution coefficients of Gd3+ and Y3+ ions in GdxY1-xCOB crystal are 0.952 and 1.069, respectively, which were measured by X-ray fluorescent analysis. So Y3+ ions are easier to incorporate into GdxY1-xCOB crystal lattice than Gd3+ ions. The composition of crystal from the seed to the bottom is homogeneous. The noncritical phase-matching (NCPM) third-harmonic generation (THG) of Nd: YAG laser (1064 nm) can be realized in Gd0.37Y0.63COB crystal along the Y-principal axis. The UV cutoff of Gd0.37Y0.63 COB is at 320 nm when measured by HITARCHI U-3500 spectrophotometer. For the first time, THG experiments of Gd0.37Y0.63COB crystal were performed using Q-switched Nd: YAG laser. The output energy is up to 88.2 mJ at 355 nm when the input energy is 600mJ for 11mm long Gd0.37Y0.63COB crystal. The THG optical-optical conversion efficiency of Gd0.37Y0.63COB crystal is 14.7%. © 2000 Elsevier Science B.V. All rights reserved.