The effect of gallium substitution on the magnetic hyperfine field of manganese-ferrite at 20 K has been studied by Mossbauer spectroscopy. It was found that the value of the magnetic hyperfine field decreases when a small concentration x of Ga3+ ions replaces the Fe3+ ions in MnFe2-xGa2O4. An increase in the magnetic hyperfine field was observed when the amount x of gallium increased (x >= 0.4). No spin canting was observed and all the samples had a collinear structure. The variation of the magnetic hyperfine field with gallium concentration is explained qualitatively on the basis of supertransferred hyperfine interaction. (c) 2005 Elsevier B.V. All rights reserved.