The fracture of single crystal, stoichiometric MgAl2O4 spinel, was investigated for the (1 0 0), (1 1 0), and (1 1 1) from room temperature to 1500° C. Two regions of fracture behaviour were observed; a low temperature elastic region where K lc decreased with increasing temperature, and an elevated temperature region where K lc increased rapidly with increasing temperature. The elastic region is explained primarily by the decrease of elastic modulus with increasing temperature, whereas the rapid increase of K lc at elevated temperature is attributed to plastic flow in the vicinity of the crack tip