Single crystals of (YbxGd1-x)(3)Ga5O12 (0.0 <= x <= 1.0) have been grown by the micro-pulling-down method. Formation of continuous solid solutions with a garnet structure was confirmed. Composition dependence of the lattice constant, thermal diffusivity, specific heat capacity and thermal conductivity was investigated. Assignment of the Yb3+-energy levels in Gd3Ga5O12- host lattice has been performed by using absorption, emission and Raman spectroscopy measurements at both, room temperature and at 12 K. (C) 2006 Elsevier Ltd. All rights reserved.