Temperature dependent X-ray diffraction measurements were performed on two samples with AlSb epilayers of differing thickness grown on GaSb by molecular beam epitaxy to determine the temperature dependence of the lattice constant (a(AlSb)) and the Poisson ratio of AlSb between 32 and 546 degrees C. At 32 degrees C, a(AlSb) was found to be 6.1361 angstrom, which is in good agreement with previous work. At higher temperatures, it differed significantly from the linear extrapolation of previously published values (below. 67 degrees C). A polynomial was fitted to the results: a(AlSb) = 6.1353+2.85 x 10(-5)T + 6.11 x 10(-9)T(2) (angstrom). The Poisson ratio was found to be approximately constant up to 300 degrees C while decreasing above. (C) 2011 Elsevier B.V. All rights reserved.