This final report covers the results of measurements that the National Bureau of Standards (NBS) made of ten half-core oil shale samples to determine their electromagnetic (EM) properties of permittivity (dielectric and attenuation constants) as a function of frequency. The samples were furnished by Laramie Energy Technology Center (LETC), Laramie, Wyoming, and were taken from a core which was drilled between Occidental's retorts #7 and #8 near Rifle, Colorado. The measurements were taken within the frequency range of 1 - 2000 MHz at various frequency intervals. The use of EM properties of permittivity to characterize oil shale for electromagnetically mapping a retort is one possible technique being considered by the DOE for determining the state of a retort prior to its ignition. There is presently no economical method of measuring the state of a cold retort, and therefore no way to predict the efficiency of the retort prior to its ignition.