PHB-U-IC has been prepared for the first time by the cocrystallization Method. The : Structure and conformation of poly(3-hydroxybutyrate),(PHB) chains encapsulated in urea (U) channels formed in the PHB-U inclusion complex (PHB-U-IC);were studied by DSC, FTIR., and solid-state NMR spectroscopy. The XRD pattern :and FTIR. spectroscopy demonstrated that PHB-U-IC takes a different crystal structure than the well reported hexagonal and trigonal crystal structures Of polymer Urea inclusion compounds. PHB-U-IC takes an expanded tetragonal,crystal structure. The conformation of PHB in the confined environment has been characterized by solid-state NMR spectroscopy and shown that PHB adopts a conformation similar, to bulk PHB. The crystallization and thermal;: properties of as received PHB and PHB coalesced from its U-IC were compared and demonstrated that the coalesced PHB Crystallizes much slower than as received PHB: Crystallinity of nonisothermally Melt crystallized as received PHB was found to be significantly higher than the crystallinity of nonisothermally melt crystallized coalesced PHB, indicating, that coalesced PHB is not easily converted into semicrystalline PHB.