Dielectric measurements of powdered forest fire ash have been investigated and presented using the Nicholson Ross Weir method within a WR-90 waveguide (X-band 8-12 GHz). The dielectric measurements of five samples have been outlined and taken at a room temperature of 22.8 degreesC. Permittivity e for five different species has been presented within this letter. These include Eucalypt, Bracken Fern, She Oak, Wattle, and Cypress. The Eucalypt sample was tested dry and with a 30% moisture content by weight. The dry Eucalypt sample was found to have a permittivity value of approximately 2.32 ± 0.025 with a loss tangent of 0.005 ± 0.0025.