The PbFe x V 6؊x O 11 series adopting the R block structural type were investigated by both powder neutron di4raction and MoK ssbauer spectroscopy in order to quantify a Fe 3؉ cation occupancy in available crystallographic sites. Four samples with formal x ratio of 1, 1.21, 1.6, and 1.75 were investigated. The results obtained from the two techniques match rather well, providing reliable re5nements. The preferential vanadium substitution by iron is clearly indicated in M(4) triangular bipyramidal sites, while M(2) and M(3) dimers are statistically occupied by Fe and V. Finally, the layers of octahedral M(1) sites remain solely occupied by vanadium. For the latter, MoK ssbauer and neutron di4raction results slightly diverge because of the possible consideration of iron species within impurities present in the samples. The 2 K crystal structure re5nement for PbFe 1.75 V 4.25 O 11 is similar to that of the room temperature form, although there is a surprising c stacking axis increase. We have already described the magnetic ZFC/FC strong irreversibility in these series and assigned it to frustration arising in M(1)O 6 layers. The magnetic structure re5nement con5rmed this model as possible in an identical magnetic/crystallographic unit cell.