The authors of this book provide recent research on conductive materials and composites. Chapter One studies the electromagnetic properties of microwire composites CoFeNiBSiMo, CoFeSiB and CoFeBSiCr, in the X and Ku band frequency. Chapter Two presents the results of the investigation of microstructure, electrical conductivity of nanocarbon-polymer composites, and the parameters of interaction with microwave electromagnetic radiation (EMR). Chapter Three reviews the shielding effectiveness of conductive materials and composites. The final chapter provides insight in the procedures of dispersion, distribution, and network formation during the melting processes of carbon black-filled nanocomposites.