A series of double B mixed perovskite oxides La0.75K0.25Mn1-xFeO3 (x = 0.2-0.5) were synthesized under mild hydrothermal conditions and characterized by powder X-ray diffraction, SEM, ICP, XPS, iodometric titration, and SQUID. All the compounds corresponded to orthorhombic structure of space group Pnma and presented a cuboid morphology. The oxidation state of Fe is +3 whereas Mn is a mixed valence of Mn3+/Mn4+. The curves M vs. T for all the compositions indicated the coexistence of ferro- and antiferromagnetic contribution.