The molecular morphology and the nature of the bound solvent in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 5 and 12% valerate content in o-dichlorobenzene were investigated by thermal analysis and polarized optical microscopy. In addition, porous particles were prepared through a phase separation process. When the PHBV/o-dichlorobenzene solution was quenched in ice-water, a white turbidity was obtained, suggesting the occurrence of a phase separation due to density fluctuations due to the formation of spherulites. The average spherulite diameter for the PHBV5 system was larger than that for the PHBV12 system because of the smaller amount of structural defects present in PHBV5. The melting behavior of o-dichlorobenzene trapped in PHBV/o-dichlorobenzene resulted in two endothermic DSC peaks. One has almost the same temperature as the melting temperature of pure o-dichlorobenzene, corresponding to solvent in a free state. The other peak was observed at a lower temperature than the melting temperature of pure solvent, corresponding to bound solvent. These two types of solvent are assumed to correspond to that in inter- and intra-spherulite regions, respectively. The solvent in the intra-spherulite regions for PHBV12/o-dichlorobenzene was larger than that for the PHBV5 system. This is due to the higher HV content which makes the noncrystalline region larger. The melting temperature of the lamellar crystals was almost the same for the PHBV5 and PHBV12 systems, but increased with concentration. The lamellar thickening at a high concentration makes the noncrystalline region smaller, resulting in a decreased coagulation size of the solvent. After excluding the solvent, porous particles were obtained. The pore size as well as the particle size was governed by the concentration of PHBV and the HV content.