This paper presents the results of H-2 Mims and H-1 Davies pulsed ENDOR of the [3Fe-4S](+) cluster of Desulfovibrio gigas hydrogenase. It also describes the first H-2 Mims pulsed TRIPLE-resonance experiments, on the exchangeable deuterons. The H-1 ENDOR data show that the intrinsic isotropic hyperfine couplings for the beta-CH2 protons of the three cysteines bound to iron fall in the range 1.3 less than or similar to a less than or similar to 1.9 MHz. These values, which often had been estimated at a = 1 MHz, will allow better interpretation of solution NMR data for paramagnetic [nFe-mS] clusters. The spectra show well-resolved signals from three strong NH...S H-bonds to the cluster. Mims H-2-H-2 TRIPLE-resonance has been used to assign the exchangeable deuterons and to obtain relative signs of the H-1,H-2 hyperfine couplings. Analysis of the hyperfine interactions in terms of spin-coupling among the three Fe(III) ions of the cluster, along with examination of the X-ray structures of several [3Fe-4S](+) clusters, gives an intrinsic hyperfine coupling of a(H-1) similar to 3-4 MHz for each of the three strong H-bonds and actually allows us to propose the distribution of H-bonds among the seven sulfur atoms within the [Fe3S4(CYs)(3)](2-) center.