The response of oil shale rods to microwave radiation in the frequency range 2 to 4 GHz is studied. The study indicates that oil shale rods are capable of sustaining wave guide modes (low Q). However, the precise nature of the modes is not yet very clear. Anisotropy effects show up in higher order modes. The loss of moisture in the shale rods leads to an increase in the resonant frequencies. 6 refs., 19 figs.