This study investigates the degradation of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) compound under various environmental conditions, including natural and laboratory settings. The research group employed multiple methodologies to assess visual and mass changes, mechanical and morphological properties, spectroscopic and structural characterization, and thermal behavior. Key findings include: 1. **Visual and Mass Changes**: T-PHBV bars showed greater degradation in natural estuarine mud compared to seawater under laboratory conditions. After 12 months in Mediterranean seawater, no significant changes were observed, except for reddish slime fouling. In the North Sea, biofouling accumulation was observed over time. 2. **Mechanical Properties**: T-PHBV exhibited typical brittle behavior with early rupture before yielding. Mechanical properties decreased significantly after soil burial and climate chamber aging, particularly in the first few weeks. In seawater, mechanical properties decreased relatively slowly over time. 3. **Spectroscopic Characterization**: ATR-FTIR spectra showed slow hydrolytic degradation in seawater, with an increase in –OH groups. No significant changes were observed in home compost and freshwater environments. 4. **Molecular Characterization**: GPC analysis revealed a clear depolymerization process, with molecular weight decreases in soil and climate chamber-aged samples. Marine environment exposure did not significantly affect molecular weight. 5. **Thermal Behaviour**: TGA and DSC analyses showed no significant changes in thermal stability after exposure to marine environments. Crystallinity decreased, indicating a reduction in crystallinity from about 60% to about 40%. 6. **Morphological Properties**: SEM images confirmed surface erosion in seawater and estuarine mud, with more pronounced erosion in mud. Surface porosity increased in composted and freshwater environments, indicating enhanced biodegradability. The study concludes that PHBV degrades under various environmental conditions, with different rates and mechanisms depending on the specific conditions. The multi-faceted approach used in this study provides robust and reliable insights into the degradation behavior of PHBV-based compounds.This study investigates the degradation of a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) compound under various environmental conditions, including natural and laboratory settings. The research group employed multiple methodologies to assess visual and mass changes, mechanical and morphological properties, spectroscopic and structural characterization, and thermal behavior. Key findings include: 1. **Visual and Mass Changes**: T-PHBV bars showed greater degradation in natural estuarine mud compared to seawater under laboratory conditions. After 12 months in Mediterranean seawater, no significant changes were observed, except for reddish slime fouling. In the North Sea, biofouling accumulation was observed over time. 2. **Mechanical Properties**: T-PHBV exhibited typical brittle behavior with early rupture before yielding. Mechanical properties decreased significantly after soil burial and climate chamber aging, particularly in the first few weeks. In seawater, mechanical properties decreased relatively slowly over time. 3. **Spectroscopic Characterization**: ATR-FTIR spectra showed slow hydrolytic degradation in seawater, with an increase in –OH groups. No significant changes were observed in home compost and freshwater environments. 4. **Molecular Characterization**: GPC analysis revealed a clear depolymerization process, with molecular weight decreases in soil and climate chamber-aged samples. Marine environment exposure did not significantly affect molecular weight. 5. **Thermal Behaviour**: TGA and DSC analyses showed no significant changes in thermal stability after exposure to marine environments. Crystallinity decreased, indicating a reduction in crystallinity from about 60% to about 40%. 6. **Morphological Properties**: SEM images confirmed surface erosion in seawater and estuarine mud, with more pronounced erosion in mud. Surface porosity increased in composted and freshwater environments, indicating enhanced biodegradability. The study concludes that PHBV degrades under various environmental conditions, with different rates and mechanisms depending on the specific conditions. The multi-faceted approach used in this study provides robust and reliable insights into the degradation behavior of PHBV-based compounds.