A detailed study of fluid flow and heat transfer characteristics in porous matrices has been performed. Refined prediction methods for pressure and temperature distribution in porous matrices have been developed to include the effects of gas conduction, internal heat sources, chemical reaction, non-steady state flows and slip flow. The show system feasibility, a high-temperature multilayer matrix system has been developed. Six specimens, one inch in diameter, were fabricated and tested in an oxyacetylene flame with and without transpiration cooling. Some tests were performed under a cold wall heat flux of 235 Btu/ft sq-sec. It was found that the specimens can withstand a surface temperature of over 3600 F for a period of 30 minutes. Thus, it has been demonstrated that a transpiration cooled thermal protection system may be developed for space vehicle applications. (Author).