Abstract <p>In this work, nanopowders of the Bi_{1 − <i>x</i>}Ba_<i>x</i>FeO₃ system (<i>x</i> = 0, 0.10, 0.20) were synthesized by the combustion method of nitrate-organic precursors. The effect of doping bismuth ferrite (BiFeO₃) with barium (Ba) ions on the morphology, crystal structure, and photocatalytic activity of the material was studied. X-ray diffraction analysis showed that all samples crystallize into a rhombohedrally distorted perovskite structure with the <i>R</i>3<i>c</i> space group. Doping with barium led to a significant decrease in the crystallite sizes, as well as to a distortion of the crystal lattice. In the case of 20% substitution, the formation of BaCO₃ impurity was observed, which was also confirmed by the analysis of the Raman spectra. It was shown that the introduction of barium leads to the formation of a more porous texture and a significant increase in the specific surface area of the material. The original BiFeO₃ demonstrated an extremely low efficiency of methylene blue decomposition relative to photolysis, while doping with barium led to a significant improvement in the photocatalytic characteristics of the material: in the case of 20% Ba substitution, the decomposition of methylene blue reached 99% in 1 h.</p>