MICROWAVE ABSORBING PROPERTIES OF La0. 67Ba0. 33Mn1-xNixO3. The doped lanthanum manganites have unusual magnetic and transport properties, which makes it possible for this material to be used for microwave absorbing. In this study, La0. 67Ba0. 33Mn1-xNixO3 (x= 0, 0.02, 0.04, and 0.06) were prepared by solid state reaction method as microwave absorption material. The crystal structure and magnetic properties were characterized by X-Ray Diffractometer (XRD) and Vibrating Sample Magnetometer (VSM), respectively. Refinement results of X-Ray diffraction pattern using High Score Plus Software showed that the samples with various x= 0 to x= 0.04 had a single phase with monoclinic crystal structure, while the sample with x= 0.06 had two phases with monoclinic and hexagonal structures. Hysteresis loops showed that the La0. 67Ba0. 33Mn1-xNixO3 (x= 0, 0.02, 0.04, and 0.06) samples are soft magnetic materials. Microwave absorption properties were investigated in the frequency range of 8-12 GHz using Vector Network Analyzer (VNA). An optimal reflection loss of-8.85 dB is reached at 11.58 GHz for x= 0.04 with sampel thickness of 2 mm.