The results of the development and utilization of an affine magnetic sorbent with Ni2+ ions immobilized on coal ash microspheres are reported. The applicability of the material in the isolation of Histag proteins is demonstrated by examples of the recombinant green fluorescent protein from Clytia gregarium and the Ca2+ regulated photoprotein obelin from Obelia longissima. The specific sorption capacity of the sorbent was 2-7 mg/cm3 for medium-size proteins (20-30 kDa). The particles are suitable for chromatography with the presence of chaotropic agents and EDTA. They are easy to manipulate as isolation of a target protein takes 30-35 min. On one hand, the elevated affinity of the sorbent to proteins rich in native histidines may result in a high degree of irreversible sorption; on the other hand, it allows isolation of such proteins without the introduction of artificial polyhistidine tracts.