Porous Al has been produced by the evaporation and sputtering of Al in argon on Si and SiO2 surfaces. The argon pressure can be varied between 0.5 and 40 mTorr to change the porosity. Porous Al consists of elongated chambers perpendicular to the surface with considerable lateral interconnection. The films are of interest since they markedly enhance heat transfer. Silicon substrates so treated dissipate considerably more power permitting higher circuit densities and increased circuit speeds. Measurements with Freon 113 have demonstrated a cooling capacity of 37 W/cm2. © 1982, The Electrochemical Society, Inc. All rights reserved.