The equiatomic iron-silicides T FeSi as well as the corresponding germanides T FeGe with the electron-poor 4 d and 5 d transition metals ( T =Zr, Nb, Hf, Ta) have been synthesized from the elements by arc-melting. All samples were characterized through their lattice parameters using powder X-ray diffraction (Guinier technique). Four structures were refined from single-crystal X-ray diffractometer data: a =640.16(3), b =393.45(5), c =718.42(6) pm, Pnma , 390 F 2 values, 20 parameters, wR 2=0.0294 for ZrFeSi (TiNiSi type), a =719.63(11), b =1119.27(7), c =649.29(7) pm, Ima 2, 1103 F 2 values, 54 parameters, wR 2=0.0555 for NbFeGe (TiFeSi type), a =655.96(7), c =372.54(4) pm, P 6̅2 m , 251 F 2 values, 15 parameters, wR 2=0.0260 for HfFeGe (ZrNiAl type) and a =624.10(3), b =378.10(6), c =725.25(7) pm, Pnma , 369 F 2 values, 20 parameters, wR 2=0.0513 for TaFeGe (TiNiSi type). The common structural motif of the four different structures is the slightly distorted tetrahedral tetrel ( tr ) coordination of the iron atoms and a trigonal prismatic coordination of iron by T =Zr, Nb, Hf, Ta. Three compounds were characterized as Pauli-paramagnetic by measuring their susceptibility. The measurement of the electrical resistivity of NbFeSi characterises this compound as a good metal. Furthermore, 57 Fe Mössbauer spectra of all compounds could be obtained at room temperature, revealing a clear correlation between the structural distortions and the quadrupole splitting parameters.