Cubic cesium leucite-based compounds, namely cesium leucites, cesium sodium leucites, and cesium lithium leucites, were synthesized using a multistep solid-state reaction method. The thermal expansion properties, in the temperature range of 298-1273 K, for the synthesized cubic cesium leucite-based compounds were examined using high-temperature powder X-ray diffractometry data. The thermal expansions of the cubic cesium leucite-based compounds were found to vary with the chemical composition. For instance, the thermal expansions of Cs0.7Na0.2Al0.9Si2.1O6 and Cs1.7Li0.2Al0.9Si2.1O6 were 0.14% at 1273 K and 0.081% at 1073 K, values lower than those of Cs0.9Al0.9Si2.1O6, which were 0.16% at 1073 K and 0.2% at 1273 K. The results showed that the thermal expansions of the cubic cesium leucite-based compounds changed with ionic substitution at the Cs+ sites because of ionic size differences between Cs+ and the Na+ or Li+ substitutional ions.