In n-type CdS, grown from the vapor phase, small-angle grain boundaries imaged by the electron-beam-induced current mode of scanning electron microscopy exhibit black-line and bright-halo contrast. Transient capacitance spectra show a peak with DELTA H approximately equals 0. 9 ev, which is related to the grain boundaries and whose variation with refilling-phase duration is that of an extended defect. Its emission characteristics are the same as those of the so-called X center, which is described in the literature as a point defect and whose electron emission is followed by an appreciable lattice relaxation. The peak in the transient capacitance spectra is therefore attributed to clouds of X centers which surround the dislocations within the grain boundaries. Refs.