The best p-type skutterudites so far are didymium filled, Fe/Co substituted, Sb-based skutterudites. Substitution at the Sb-sites influences the electronic structure, deforms the Sb4-rings, enhances the scattering of phonons on electrons and impurities and in this way reduces the lattice thermal conductivity.In this paper we study structural and transport properties of p-type skutterudites with the nominal composition DD0.7Fe2.7Co1.3Sb11.7{Ge/Sn}0.3, which were prepared by a rather fast reaction–annealing–melting technique. The Ge-doped sample showed impurities, which did not anneal out completely and even with ZT>1 the result was not satisfying. However, the single-phase Sn-doped sample, DD0.7Fe2.7Co1.3Sb11.8Sn0.2, showed a lower thermal and lattice thermal conductivity than the undoped skutterudite leading to a higher ZT=1.3, hitherto the highest ZT for a p-type skutterudite. Annealing at 570K for 3days proved the stability of the microstructure. After severe plastic deformation (SPD), due to additionally introduced defects, an enhancement of the electrical resistivity was compensated by a significantly lower thermal conductivity and the net effect led to a record high figure of merit: ZT=1.45 at 850K for DD0.7Fe2.7Co1.3Sb11.8Sn0.2.