The synthesis, crystal structure, and physical characterization of five new radical salts formed by the organic donor bis(ethylenediseleno)tetrathiafulvalene (BEST) and the paramagnetic tris(oxalato)metalate anions [M(C2O4)(3)](3-) (M = Fe-III and Cr-III) are reported. The salts isolated are (BEST)(4)[M(C2O4)(3)]center dot PhCOOH center dot H2O with M-III = Cr (1) or Fe (2) (crystal data: 1, triclinic, space group P (1) over bar with a = 14.0999(4) angstrom, b = 15.3464(4) angstrom, c = 19.5000(4) angstrom, alpha = 76.711(5)degrees, beta = 71.688(5)degrees gamma = 88.545(5)degrees V = 3893.5(2) angstrom(3), and Z = 2; 2, triclinic, space group P (1) over bar with a = 14.0326(3) angstrom, b = 15.1981(4) angstrom, c = 19.4106(4) angstrom, alpha = 76.739(5)degrees, beta = 71.938(5)degrees, gamma = 88.845(5)degrees, V = 3824.9(2) angstrom(3), and Z = 2), (BEST)(4)[M(C2O4)(3)]center dot 1.5H(2)O with M-III = Cr (3) or Fe (4) (crystal data: 3, monoclinic, space group C2/m with a = 33.7480(10) angstrom, b = 12.3151(7) angstrom, c = 8.8218(5) angstrom, beta = 99.674(5)degrees, V = 3614.3(3) angstrom(3), and Z = 2; 4, monoclinic, space group C2/m with a = 33.659(6) angstrom, b = 12.248(2) angstrom, c = 8.759(2) angstrom, beta = 99.74(3)degrees, V = 3558.9(12) angstrom(3), and Z = 2), and (BEST)(9)[Fe(C2O4)(3)](2)center dot 7H(2)O (5) (crystal data: triclinic, space group P (1) over bar with a = 12.6993(3) angstrom(3), b = 18.7564(4) angstrom, c = 18.7675(4) angstrom, alpha = 75.649(5)degrees, beta = 107.178(5)degrees, gamma = 79.527(5)degrees, V = 3977.5(3) angstrom(3), and Z = 1). The structures of all these salts consist of alternating layers of the organic donors and tris( oxalato) metalate anions. In 1 and 2 the anionic layers contain also benzoic acid molecules H-bonded to the terminal oxygen atoms of the anions. In all salts the organic layers adopt beta-type packings. Along the parallel stacks the donors form dimers in 3 and 4, trimers in 5, and tetramers in 1 and 2. All the compounds are paramagnetic semiconductors with high room-temperature conductivities and magnetic susceptibilities dominated by the Fe- or Cr-containing anions.