Abstract-In this work will be presented the results obtained in the synthesis and structural and morphological characterization of perovskite oxide Barium Hafnate (BaHfO3) synthesized by the hydrothermal method assisted by microwave (MAH) with two concentrations of potassium hydroxide (KOH). One with concentration of 2.4M which will be called BHO24 and another one of 3.6 M which will be called BHO36, in order to reduce the difference between the amount of reagents (in this case barium chloride and hafnium chloride-Bacl2 and HfCl4) and the amount of mineralizing agent (in this case KOH) used in synthesis through the MAH. The objective of this study is to analyze the possibility of synthesizing a perovskite oxide by MAH with the minimum amount of KOH and to analyze if there is any change in the structure or morphology of the same. To analyze the structural change, the X-ray diffraction (XRD) and to analyze the morphological change was used the characterization technique of scanning electron microscopy (SEM).