High frequency (95 GHz, W-band) pulsed ENDOR measurements were carried out on the Fe-57-containing zeolites : Fe-sodalite (FeSOD), Fe-L (FeLTL), Fe-mazzite (FeMAZ), and Fe-ZSM5 (FeMFI), where Fe-57(III) was introduced during synthesis. The echo-detected EPR spectra of all zeolites investigated, recorded at 1.8 K, show mainly the -5/2] to -3/2] EPR transition. Accordingly, the ENDOR spectra exhibit only two Fe-57 ENDOR transitions at 67.8-68.8 and 39.0-39.6 MHz, corresponding to M(s) = -5/2 and -3/2, respectively. From these frequencies isotropic hyperfine couplings of -29.0, -29.3, -29.5, and -29.6 MHz were derived for (FeSOD)-Fe-57, (57)FeL, (57)FeMAZ, and (57)FeMFI, respectively. On the basis of an earlier assignment of the g = 2 signal in FeSOD to Fe(III) in tetrahedral framework sites it is concluded that hyperfine couplings in the range -29.0 to -29.6 MHz are characteristic of Fe-57(III) in zeolite frameworks. In contrast to the X-band Fe-57 ENDOR signals, the W-band signals are free from second- and third-order contributions of the hyperfine and zero-field splitting (ZFS) interactions and are thus significantly simpler to assign and interpret. The ZFS contributions caused excessive inhomogeneous broadening of the X-band ENDOR spectra of (57)FeL, (57)FeMAz, and (57)FeMFI and the detection of the ENDOR spectra was practically impossible : All zeolites studied exhibited ENDOR signals from Al-27 and (FeSOD)-Fe-57 showed also clear Na-23 ENDOR signals. The hyperfine interaction of the Na-23 was significantly larger than that of the Al-27, confirming the assignment of the Fe(III) to framework sites, substituting for Al. Moreover, the value obtained for the Na-23 anisotropic hyperfine component, 0.53 MHz, corresponding to a distance of 3.4 Angstrom, is in good a agreement with the known structure of sodalite where the distance between a framework atom and the Na+ cations in the center of the six rings is 3.35 Angstrom. This work demonstrates the power and potential of high-field ENDOR in terms of resolution, signal assignment, and spectral analysis.