The bulk ionic conductivity of various sodalites (synthesized by the structure conversion method) and their starting materials, Linde molecular sieves, has been investigated over a temperature range between 300 to 700°K in a vacuum enclosure. The Arrhenius plots of these data indicate a single activation process. X-ray diffraction studies verify the conversion of molecular sieves into sodalite structures and also indicate that the unit cell parameter in sodalite is dependent upon the anion incorporated. The conductivity of sodalite is found to be dependent upon the unit cell parameter. Of the different materials studied, Cl-, Br-, I-sodalites and molecular sieves show progressively increasing conductivity and decreasing activation energy. The effect of adding sulfur to the sodalites is to raise the conductivity and lower the activation energy, relative to the undoped sodalites. These results are explained by a model based on the collapsing of the aluminosilicate framework into sodalite under the influence of the various halogens. © 1974 American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.