In the present paper the formation of high strength structures of WC-Co and W-Ni-Fe-Co composite materials is investigated and optimal operating parameters are defined. Tungsten carbide-cobalt and W-Ni-Fe-Co composites were produced by the method of high-voltage electrical discharge together with application of mechanical pressure to powder compact. It was found that the density and hardness of composite material reach its maximum values at certain magnitudes of applied pressure and high-voltage electrical discharge parameters. We show that there is an upper level for the discharge voltage and applied pressure beyond which the powder of composite material disintegrates like an exploding wire. We have invented a mathematical model of powder material behavior in volumetric energy emission which is based on the laws of conservation of mass, impulse and energy together with electrodynamics equations. Equations of state of powder materials have been used with account of experimental results obtained. Our analysis has been carried out from the modern viewpoints of thermodynamics of irreversible processes in open systems. Due to our results it is possible to determine optimal parameters for electro-discharge compaction of WC-Co and W-Ni-Fe-Co powder materials with preset properties.