Electrical properties of graphite flake (GF) filled polyphenylene sulphide (PPS) composites prepared by hot pressing was investigated to be used for electromagnetic interference (EMI) shielding applications. Composites exhibited an electrical conductivity percolation threshold of 5 wt%. The electrical conductivity of composites was increased fourteen orders of magnitude higher than that of pure PPS. The dielectric constants and dissipation factor of composites were measured in a frequency range of 100 KHz to 15 MHz. The dielectric constant of the composites increased several orders of magnitude and showed a strong dependence on frequencies. For example, dielectric constant of 8 wt% composite measured at 1 MHz was increased by five orders of magnitude compared to pure PPS. Similarly, dissipation factor was increased significantly. Scanning electron microscopy showed 3-dimensional conducting network of GF across the PPS matrix. Significant improvement in electrical properties shows that these composites may be useful for EMI shielding particularly at high temperature applications.