Rust is the by product of oxidation on ferrous metal. Rust is extremely harmful and can’t be avoided. Due to that reason for added values on rust a research titled utilizing corrosion product as absorber for microwave on X-band frequency is done. This research goals are to determine the ability of rust to absorb radar waves by maximum reflection loss values. The study was conducted by taking a powder natural ferrites of rust from corroded ferrous metal in Surabaya, Malang, Bangkalan and then later separated by using a 0.1 T hard magnet. The XRF, XRD and VSM characterization showed that rust powder sample has chemical compound of ferrites (Fe3O4) with magnetite phase and a soft magnetic with Ms = 8 emu/g. Based on the measurement microwave absorbing by VNA showed that maximum reflection loss of natural ferrites Surabaya, Malang, Bangkalan respectively-20.15 dB,-12.64 dB and-6.75 dB, at matching frequency 11 GHz and width frequency 3 GHz.