This study investigates the mechanical and thermal properties of polypropylene (PP) composites reinforced with hemp natural fibers processed with sodium hydroxide (NaOH). The fibers were treated with NaOH at 5% concentration for 60 minutes, followed by washing and drying. The composites were prepared using the compression molding method with fiber loadings of 0, 10, 20, and 30 wt%. The mechanical properties, including tensile and flexural strength, and thermal properties, such as thermal mass loss, were evaluated according to ASTM standards. The results showed that the 30 wt% NaOH-treated hemp fiber composite exhibited significantly improved tensile and flexural strength (47 ± 1 MPa and 69 ± 2 MPa, respectively) and a lower thermal mass loss of 6%. These enhanced mechanical and thermal properties make the composite suitable for automotive roof frame applications. The study also highlights the importance of chemical processing in improving the adhesive strength and overall performance of natural fiber-reinforced composites. The results indicate that NaOH treatment enhances the physical and chemical properties of the composite, leading to better mechanical and thermal performance compared to mono-PP. The study emphasizes the potential of natural fiber-reinforced composites in various engineering applications due to their biodegradability, environmental sustainability, and improved mechanical properties. The compression molding process is recommended for producing composites with desired shapes and cost-effectiveness. The findings suggest that the use of NaOH-treated hemp fibers in PP composites can lead to significant improvements in performance, making them a viable alternative to conventional materials.This study investigates the mechanical and thermal properties of polypropylene (PP) composites reinforced with hemp natural fibers processed with sodium hydroxide (NaOH). The fibers were treated with NaOH at 5% concentration for 60 minutes, followed by washing and drying. The composites were prepared using the compression molding method with fiber loadings of 0, 10, 20, and 30 wt%. The mechanical properties, including tensile and flexural strength, and thermal properties, such as thermal mass loss, were evaluated according to ASTM standards. The results showed that the 30 wt% NaOH-treated hemp fiber composite exhibited significantly improved tensile and flexural strength (47 ± 1 MPa and 69 ± 2 MPa, respectively) and a lower thermal mass loss of 6%. These enhanced mechanical and thermal properties make the composite suitable for automotive roof frame applications. The study also highlights the importance of chemical processing in improving the adhesive strength and overall performance of natural fiber-reinforced composites. The results indicate that NaOH treatment enhances the physical and chemical properties of the composite, leading to better mechanical and thermal performance compared to mono-PP. The study emphasizes the potential of natural fiber-reinforced composites in various engineering applications due to their biodegradability, environmental sustainability, and improved mechanical properties. The compression molding process is recommended for producing composites with desired shapes and cost-effectiveness. The findings suggest that the use of NaOH-treated hemp fibers in PP composites can lead to significant improvements in performance, making them a viable alternative to conventional materials.