It is known that polyphenylene sulfide (PPS), which is a semi-crystalline aromatic polymer, exhibits high thermal stability, outstanding chemical resistance, and excellent flame retardancy properties. However PPS has a poor electrical and thermal conductivity, which limits their uses in some applications where thermal conductivity is required for heat dissipation or storing efficiently. In order to improve thermal conductivity of Polyphenylene sulfide (PPS), PPS-Synthetic graphite (SG) composites were produced by using twin-screw extrusion. SG at different weight fractions (10, 30, 50%) were loaded into PPS and thermal conductivity values of composites were measured in plane and through plane directions. The effect of loading SG into PPS on the mechanical properties of PPS was determined by using three-point bending tests. Charpy tests were conducted to determine the impact properties of SG loaded PPS composites. The effect of SG loading on density of PPS was also determined. Differentials canning calorimetry analyses of SG loaded PPS composites were carried out to determine Cp values. When 50 wt% SG was loaded into PPS, in plane and through plane thermal conductivity of PPS were obtained to be 6.54 and 1.5 W/mK, respectively. Considering ISO 180 standard, charpy-notched impact strengths of PPS-10SG, PPS-30SG, and PPS-50SG are determined to be 9.69, 8.75, and 7.9 kJ/m2 respectively. From conducted result it was concluded that in spite of loading of SG, the mechanical properties of PPS has not affected greatly.