A guest-host assembly having a generally spheroidal host assembly formed of trimers of calixarene molecules in a hexagonal close-packed assembly and its preparation. The calixarene trimers are associated together predominantly by van der Waals forces to provide dilated channels having void volumes within the range of 100-200 .ANG..sup.3. A guest component, such as hydrogen, methane, or another hydrocarbon or halocarbon, is encapsulated within the dilated channels of the spheroidal host assembly and retained within the channels primarily by van der Waals forces. The guest-host assembly is stable at a temperature of 150.degree. C. or higher. The temperature at which the onset of the release of the guest component occurs is within the range of 150-300.degree. C.