X-ray diffraction (XRD), electron paramagnetic resonance (EPR), and magnetic susceptibility measurements have been employed to investigate the samples from the (Gd(2)O(3)) (x) center dot(B(2)O(3))((60-x))center dot(ZnO)(40) (0 a parts per thousand currency sign x a parts per thousand currency sign 20 mol%) system. The XRD pattern for the prepared samples shows that the vitreous phase is present only for x a parts per thousand currency sign 15 mol%. For the samples containing 20 mol% Gd(2)O(3) the presence of a unique crystalline phase, GdBO(3), embedded in a vitreous matrix was evidenced. In this case the XRD patterns show the presence of nanometer sized crystals (64 nm) in a glassy matrix. The EPR spectra of the studied samples exhibit three important features with effective g-values of a parts per thousand 6, 2.8, 2.0 and a weaker feature at g a parts per thousand 4.8. For low Gd(2)O(3) contents (x < 3 mol%), the EPR spectra have the typical ''U''-type shape. For higher contents of Gd(2)O(3) (x a parts per thousand yen 3 mol%), the spectral features are broadened and finally are dominated by a single broad absorption line located at g a parts per thousand 2.0. This broad EPR line is associated to the Gd(3+) ions present predominantly as clustered species. Magnetic susceptibility data show that for x > 1 mol% the Gd(3+) ions are present not only as isolated species but also as species coupled through antiferromagnetic exchange interactions.