The mechanism of formation of zinc ferrite (ZnFe2O4) from ZnC2O4 center dot 1.8H(2)O-2Fe(II)C(2)O(4)center dot 2H(2)O and ZnC2O4 center dot 1.8H(2)O-Fe-2(III) (C2O4)(3)center dot 6H(2)O mixtures is investigated. By combination of TG and XRPD measurements it has been shown that microcrystalline ZnFe2O4 forms from physical mixtures after prolonged annealing at 1000 degrees C while nanocrystalline ZnFe2O4 powders are produced by mild annealing (1 h at 500 degrees C in air) of mechanically activated mixtures. The magnetic properties of ZnFe2O4 powders obtained from physical and from milled mixtures are compared. (C) 2006 Elsevier B.V. All rights reserved.