The paper proposes a simple one-stage synthesis of ferrite/biochar composites based on oxide compounds of NixCo1-xFe2O4 (х = 0, 0.5, and 1). The obtained materials were characterised using x-ray diffraction patterns, Fourier transform infrared (FTIR) spectrometry, electron microscopy, Scherrer and Williamson-Hall methods. The high photocatalytic activity of the synthesised materials in the process of methyl orange oxidative degradation at hydrogen peroxide presence has been established. It is noted that the highest catalytic activity is exhibited by the composite material based on cobalt (II) ferrite and sunflower biochar: in their presence, it is possible to achieve 100% removal of the dye after 120 and 90 min, respectively. A possible mechanism of the dye decomposition process is discussed.