Abstract: Microwave spectroscopic properties of imidazolium-based ionic liquids has been investigated in the 100 MHz to 10 GHz range over a range of temperature between 25 oC and 125 oC for characterising the dielectric and loss factor properties. The room temperature dielectric properties of the ionic liquids were found to decrease with increasing frequency of incident wave which may be attributed to a net drop in polarization, as some polarization mechanisms example interfacial and orientation polarization cease to contribute at higher frequencies.