Conjugated polymers (CPs) with various conductive fillers have recently attracted much attention because of their suitability in various fields like in electronic devices, rechargeable batteries, sensors, supercapacitors etc. In many instances polymers need to fulfill contradictory demands which are not possible with a single polymer or mixture of two polymers. Attempts have been made earlier to incorporate plastics or insulators with CPs in order to improve the processability of the composite material without losing the mechanical properties. This book deals with chemical synthesis of carbon filled polyaniline and polypyrrole composites and evaluation of their electrical and electrochemical properties. The influences of carbon fillers like graphite, graphene oxide and expanded graphite on electrical properties of the polymer composites and their applications in sensors and supercapacitors have also been reported. We hope that this book contributes a little knowledge to the rapidly advancing field of carbon filled π-conjugated polymers and also opens up the possibilities of further research on this field.