The lattice parameter of synthetic spinel, MgAl₂O₄ has been determined over the temperature range 77-300 K. The results can be expressed in the form a=8.0739+3.565*10^-8 T²+9.90*10^-11 T³ where a is the lattice parameter in AA at T K, and are consistent with measurements previously reported for ranges of temperature above room temperature. The corresponding variation for the linear coefficient of thermal expansion is derived. This shows that spinel has a thermal expansion only slightly greater than that of silicon and of the III-V semiconductors for which materials it has been used as an epitaxial substrate.