The temperatures and the enthalpies of both solid-solid and solid-liquid phase transition were collected from the origi- nal literature published from the end of last century to early 1995. All the values were critically evaluated to pro- vide recommended values in the cases where several experi- mental values were reported for the same phase transition. The accuracies of both the original and recommended values were determined and information was given regarding the sam- ple purity and method of measurement. This volume will be useful to a wide community of researchers, specialists and engineers working in the field of physical and organic chem- istry, chemical engineering, electronics, material science, chemical aspects of energy technology, and those developing computerized predictive packages, and for universities.