Abstract: Electrically conductive, magnetic composite material, comprising (A) pulverulent, inorganic, magnetic material which is electrically not or only poorly conductive, and (B) an electrically conductive material, selected from the group consisting of pulverulent and liquid carbon-comprising organic materials and pulverulent carbon allotropes, in a ratio by weight of (A):(B)=from 1:100 to 100:1; a process for its production, and its use, and also ferrimagnetic mixed oxide (A) of the general formula I: M?M??O4??(I), in which M? is a first metal component which comprises divalent metal cations; and M?? is a second metal component which comprises trivalent metal cations; capable of production by reacting, in a quantitative ratio such that the resultant ferromagnetic mixed oxide (A) is electrically neutral, divalent metal cations M? and trivalent metal cations M?? in aqueous solution and/or dispersion, comprising at least one electrically conductive material (B) and/or at least one material which differs there