The crystal structure and thermal expansion properties of solid solutions Sc2-xAlxMo3O12(x = 0.0-2.0) are systematically investigated by X-ray diffraction. Rietveld refinement results indicate that samples with x <= 1.3 crystallize in a sc(2)Mo(3)O(12)-type orthorhombic (Pnca) structure, whereas others have an Al2Mo3O12-type monoclinic (P2(1)/a) structure. Substitution of 15% Al3+ for Sc3+ leads to a rapid change in linear thermal expansion coefficient from -2.334 x 10(-6) degrees C-1 to 0.732 x 10(-6) degrees C-1. The thermal expansion coefficients of Sc2-xAlxMo3O12 monotonously increase with increased Al3+ content. (C) 2013 Elsevier B.V. All rights reserved.