Crystal structure and temperature dependence of magnetic susceptibility and electrical resistivity have been determined for GdTiSi and GdTiGe. Both compounds order ferromagnetically and for GdTiGe TC is 374 K which is a very high value for such kinds of compounds. The electronic structure for both compounds has been investigated by photoelectron spectroscopy and compared with calculations performed using the TB-LMTO method. A very good agreement with experiment was obtained, especially for GdTiGe. A strong hybrydization between the d states from Gd and Ti was found and a significant polarization of the Ti 3d electrons in GdTiGe was obtained which may be related to the enhanced indirect exchange between Gd magnetic moments.

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The electronic structure of the compounds Gd 5 (Si, Ge) 4 has been investigated with the use of x-ray and ultraviolet photoelectron spectroscopies. The results are compared with calculations performed with the tight-binding linear muffintin orbital method for Gd 5 Si 4 and Gd 5 Ge 4 . Very good agreement with the experimental data has been obtained and conclusions about the character of the electronic states, their hybridization and their influence on magnetic and electrical properties have been drawn. The effect of Ti substitution (5 at.%) for Si or Ge in Gd 5 (Si, Ge) 4 has been investigated. Significant changes in the electronic structure near the Fermi level have been found especially for Gd 5 Si 4 .

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