In this work, the performances which are the reflection loss and absorption for composite of sugarcane bagasse (SCB) and rubber tire dust as microwave absorber were inves- tigated in the range frequency of 8.2–12.4 GHz (X-Band). Sugarcane bagasse (SCB) is one of the major agricultural wastes. This residue agricultural waste material has potential to be used as an alternative material for microwave absorber in Radio Frequency (RF) anechoic chamber. Rubber tire dust is one of the residues from tire wear. This paper shows the method about how the sample which is the composite of sugarcane bagasse with rubber tire dust was fabricated and the measurement to get the reflection loss (S11 ) and transmission coefficient (S21 ). The thick- ness of the sample is 5 mm. The methodologies included in this work are defining the dielectric properties and measurement of the samples using transmission line technique (waveguide). The dielectric constant, ε0 from the transmission line measurement of the composite of sugarcane bagasse-rubber tire dust is 3.35. The S11 results showed that the SCB-rubber tire dust compos- ite absorber was found to be better which means lower than −10 dB. The results proved that SCB-rubber tire dust was a good alternative to be used as microwave absorber. The goal of this investigation is to have the better electromagnetic reflection (S11 ) which is less that −10 dB with the usage of the new agricultural waste such as sugarcane bagasse (SCB) and rubber tire dust. These can help save the nature and environmental friendly.