The crystalline structure and magnetic properties of Mn<sub>1-x</sub>Co<sub>x</sub>Fe<sub>2</sub>O<sub>4</sub> (x = 0 & 0.25) was studied in this report. The ferrite materials were synthesized by the chemical co-precipitation method and calcinated at 1000<sup>o</sup>C for 5 hours. The obtained materials were characterized by FTIR, XRD and VSM, and for photocatalytic activity was measured by UV-Vis spectrometer. Vibration bands at tetrahedral and octahedral site were corresponded by <strong> </strong>= 581.56 cm<sup>-1</sup> and = 465.83 cm<sup>-1</sup> and 474.51 cm<sup>-1</sup> . The obtained ferrite were confirmed by XRD as spinel structure and shown that the addition of number of Mn decreased crystallite size <em>(D)</em> and x-ray density (<em>ρ<sub>x</sub></em>), but lattice constants <em>(a)</em> increased. The crystallite size of samples with x = 0.50 was 34.85 nm, and x = 0.75 was 32.17 nm. The magnetic properties of nanoparticles shown that magnetization saturation <em>(</em><em>Ms)</em>from 42.05 emu/g to 54.16 emu/g increased with the addition of number of Mn. The coercive field (<em>H</em><sub>c</sub>)decreased from 408.27 Oe to 258.37 Oe. Photocatalytic activity was observed by UV-Vis spectrometer, where percentage of MB degradation <em>(E)</em> increase with the addition of number on Mn from 49.08% to 69.06%, either rate constant <em>(k<sub>app</sub>)</em> and half life time<em> (t<sub>1/2</sub>)</em>. Furthermore, ferrite material base Mn-Co-ferrite has good characteristic to applied for photocatalyst.