Abstract: Shock responses ofporous materials are studied using the material-point method. Theeffects of porosity, mean-cavity-size, shock strength, localdivergence and vorticity are investigated. In materials with verysmall porosity, the shocked portion may arrive at a nearly steadystate; the mean pressure and density oscillate slightly due to thetension waves reflected back from the cavities in the downstreamportion. In materials with larger porosity, the shockcompressibility decreases and the attenuation of shock wavesbecomes more evident. Under fixed porosity, a highermean-cavity-size results in a higher mean temperature. Theattenuation of shock waves depends on the porosity,mean-cavity-size, and shock strength. Local turbulence mixing andvolume dissipation are two important mechanisms for transformationof kinetic energy to heat. The stronger the loaded shock, thestronger the porous effects. The pressure, density, temperatureand particle speed do not approach their equilibriums at the samerate.