The crystal structure of the compound Al2ErGe2 has been determined by X-ray powder diffraction technique and refined by using Rietveld method. The compound Al2ErGe2 crystallizes in a hexagonal Al2CaSi2-type structure (space group P (3) over bar1, a = 0.41781(9) nm, c = 0.66698(1) nm, z = 1). Lattice thermal expansion studies on the compound were carried out in the temperature range from 298 to 913 K. The variation of the unit cell parameters shows that the lattice parameters increase with the increase in temperature. The coefficients of average relative thermal expansion of the compound along various axes were presented. (c) 2008 Published by Elsevier B.V.