Poly-β-hydroxybutyrate is a natural polymer that has the potential to replace traditional polymeric materials. This study was aimed to investigate and observe the extent of biodegradation of poly-β-hydroxybutyrate. PHB was produced by growing Bacillus cereus and then PHB films were prepared by employing solvent casting method. Biodegradability of PHB was observed through CO₂ determination produced during degradation process. In addition to CO₂ evolution, scanning electron microscopy and FTIR spectroscopy were employed to determine the morphological changes and crystallinity changes in the PHB during degradation process. During degradation process 1.97 g/L of CO₂ was produced and 26.7 % degradation was observed. SEM showed formation of grooves, pits and cracking on PHB films. FTIR spectra of PHB films before and after test showed formation of some new bonds between 1300/cm to 1700/cm region due to breakage of C-O bonds. The study on the biodegradation of poly-β-hydroxybutyrate have increased our knowledge of PHB biodegradation under study conditions and suggests that this material could be applicable to single-use applications.