The low-temperature structures of the colquiriite-type fluorides LiCaAlF 6 and LiSrAlF 6 have been investigated by single crystal X-ray diffraction. Molecular orbital calculations were also carried out using cluster models based on the obtained structures. The crystallographic c-axis at 120K in LiSrAlF 6 became slightly elongated with respect to the 300K lattice and the structure became more distorted. In contrast, there was uniform lattice parameter contraction in LiCaAlF 6 and the structure changed minimally between 300 and 120K. These structural variations support other studies of temperature dependent optical properties reported in the literature.