In this study, the effects of two different biodegradable plastic additives on the thermal and mechanical properties of isotactic polypropylene were investigated, analyzed, and presented. Biosphere biodegradable plastic additive and another oxidative biodegradable plastic additive, D2W, were used in 0.25, 0.5, 1.0, 1.5, and 2.0 wt% to prepare two sets of isotactic polypropylene composites. Differential scanning calorimeter and optical polarized light microscope were used to analyze the obtained composites thermally while the mechanical properties of these composites were studied by conducting tensile and impact testing. The morphological results reveal that only monoclinic aspherulites were obtained when the polypropylene crystallizes isothermally from the melt, it was found that both biodegradable plastic additives used decreases the size of the spherulites and increases their densities per unit volume. The incorporation of the Biosphere within the polypropylene matrix raises the crystallization temperature while the existence of D2W within the matrix delays the crystallization process. The addition of 2 wt% of Biosphere allows polypropylene to crystallize at about 13◦C higher than neat poly- propylene. It has been found that the addition of the biosphere increases Young's modulus, while decreases the yield strength, the elongation at break, and the impact strength. On the other hand, D2W as an oxidative biodegradable plastic additive increases the elongation at break and the impact strength while decreases the yield strength and Young's modulus