Calcium carbonate is one of the most common fillers used in compounding of Polypropylene.Cockle seashell, a bioresource rich in calcium carbonate and readily found along the seacoast wasgrounded to fine particle size and sieved to obtain a mesh size of 150micrometer. Cockle seashell powder was compounded with polypropylene keeping the weight of polypropylene constant at 50gwhile increasing the filler loading of seashell. Seashell powder was added to the polypropylene matrix ranging from 5g - 50g. The samples were prepared using a compression molding machine. Ten samples were prepared without compatibilizer and another ten samples were prepared with Maleic Anhydride as a compatibilizer. A control sample of pure polypropylene was also prepared. The mechanical properties such as tensile strength, flexural strength, hardness and elongation at break of the samples were analyzed. Tensile strength of PP/SS samples with Maleic anhydride increased steadily and at PP/SS (50/30) had the highest tensile strength of while PP/SS samples without Maleic Anhydride had better elongation at break.PPcomposite incorporated with compatibilizer had low flexural values compared to PPcomposite without compatibilizer. However, there was no significant difference in the hardness property of the compositeswith and without compatibilizers.