Phosphate-rich metalodèvite was found in the Jánská vein, in the Březové Hory deposit, Příbram ore district, Czech Republic. It occurs as coatings and centimeter-scale aggregates associated with metazeunerite in proximity to strongly altered uraninite in a vein of quartz and sphalerite. Powder X-ray-diffraction data for metalodèvite were indexed on the structure model reported for synthetic metakirchheimerite (space group m>Pm>1), in contrast to the tetragonal cell originally proposed for metalodèvite (space group m>Pm>42/m>mm>). The refined unit-cell parameters are: m>am> 7.193(5), m>bm> 9.771(8), m>cm> 13.24(1) Å, α 75.54(6), β 84.07(6), γ 81.68(6)° and m>Vm> 889(1) Å3. The results of electron-microprobe analyses show that metalodèvite from Březové Hory contains up to 40 mol.% of the phosphate component. Such extensive substitution has not been reported previously for metalodèvite and its related phases. The thermogravimetric curve of metalodèvite exhibits several dehydration steps in the range ~20–300°C, which can be assigned to the release of molecular water, with a total weight loss of 14.70 wt.%, corresponding to 8.43 H2O m>pfum>. The empirical formula of the metalodèvite studied is: (Zn0.72Fe0.10Mg0.06Al0.05)∑0.93 (UO2)2.12[(AsO4)1.44(PO4)0.56]∑2.00·8.43H2O (mean result of seven analyses, on the basis of As + P = 2 m>apfum>). The observed content of H2O is close to the ideal reported for the crystal structures of related octahydrates. Stretching and bending vibrations in the Raman and infrared spectra were tentatively assigned to the (UO2)2+, (AsO4)3−, (PO4)3− and H2O units.