Introduction Minibeam radiation therapy (MBRT) has proven to be a promising approach to increase the tolerance of normal tissue. Hadron therapy could benefit from this effect and provide a lower impact on non-targeted tissues to allow its administration at higher doses. We proposed a new approach allying the inherent advantages of ions with MBRT combines hadron therapy with minibeam radiation therapy. Although the biological basis playing a role in MBRT are not well established, one participant is the so-called dose–volume effect; the smaller the field size, the higher the tolerances. Purpose Determine the minimum field size for Hadron MBRT that could still be used providing satisfactory dose distributions. Materials and methods For that purpose the Monte Carlo simulations (GATE v6.2 (Geant4.9.5)) of arrays of rectangular ions (C, O, Ne, Ar, Si and Fe) minibeams impinging in a water tank were evaluated. The minibeam sizes ranged from 50 to 600 μm × 2 cm. Results As figures of merit, depth dose, transversal profile, FWHM and contribution of nuclear fragments were evaluated. Although the biological experiments are needed to ultimately prove the method, physical aspects are established in this work. Conclusion The minimum minibeam size depends on the ion, but our results show beam sizes below 300 μm × 2 cm will not be adequate for Hadron MBRT.