Graphite–halogen (Br2, ICl) residue compounds have been found to be convenient temperature calibration standards for transmission electron microscopy in the medium temperature range. Due to the order–disorder transformation associated with the intralayer intercalate ordering in these intercalation compounds, the observation of the disappearance of the superlattice diffraction spots as the sample temperature is raised serves to calibrate the temperature. The transformation occurs at 100±1 °C in graphite–Br2and 41±1 °C in graphite–ICl. The simplicity of specimen preparation gives added attraction to the use of graphite–halogens as temperature calibration standards.