The title compound, tripotassium iron(III) bis-(ortho-molyb-date) dimolybdate, was obtained by a solid-state reaction. The main structural building units are one FeO6 octa-hedron, two MoO4 tetra-hedra and one Mo2O7 dimolybdate group, all with point group symmetries m. These units are linked via corner-sharing to form ribbons parallel to [010]. The three K(+) cations are located between the ribbons on mirror planes and have coordination numbers of 10 and 12. Two O atoms of one of the MoO4 tetra-hedra of the dimolybdate group are disordered over two positions in a 0.524 (11):0.476 (11) ratio. The structure of the title compound is compared briefly with that of Rb3FeMo4O15.