Аннотация:The polymorphism was studied of dibenzo-24-crown-8 by IR spectroscopy and DSC. Three forms О±, ОІ, and Оі are identified. The heats of melting are given for the О±- and ОІ-forms. The Оі в†’ ОІ transition has enthalpy of 16.6 kJ/mol. The transitions between О±, ОІ, and Оі are discussed. Possible structures for each form are derived from the IR spectra.