<p>The effects of Ag₂S addition on the electrical transport properties, microstructure, AC susceptibility and Josephson current of YBa₂Cu₃O_7−δ were investigated. Samples with the starting composition YBa₂Cu₃O_7−δ(Ag₂S)_<i>x</i> for <i>x</i> = 0, 1, 2, 5, 10, 20 and 50 wt.% were prepared using the solid state reaction method. X-ray diffraction, four-point-probe electrical resistance measurements, field emission scanning electron microscopy (SEM) and AC susceptibility techniques were used to characterize the samples. The orthorhombic structure of YBa₂Cu₃O_7−δ was preserved upon Ag₂S addition. SEM micrographs showed that the average grain size of the <i>x</i> = 10 wt.% sample decreased with Ag₂S addition. Ag₂S did not suppress the onset-transition temperature, <i>T</i>_c-onset; however, it reduced the zero-resistance temperature, <i>T</i>_c-zero. The intergranular peak temperature (<i>T</i>_p1) and intragranular peak temperature (<i>T</i>_p2) were determined from the imaginary part of the AC susceptibility. The superconducting transition temperature from AC susceptibility measurements, <i>T</i>_cχ′, defined as the onset of the diamagnetic transition in the real component (χ′) of the AC susceptibility, did not change significantly; however, <i>T</i>_p1 and <i>T</i>_p2 decreased significantly with increasing Ag₂S content. The critical current densities <i>J</i>_c(<i>T</i>_p2) ranged from 21.7 to 23.2 A cm⁻². The Josephson energy (<i>E</i>_J) reached its maximum value for the <i>x</i> = 1 wt.% sample, indicating enhanced intergrain coupling at this composition. This addition level optimizes Josephson coupling between YBa₂Cu₃O₇_−δ grains, which may be useful for designing high-coherence qubits based on granular high-<i>T</i>_c superconductors. Compared with other compound additions having different magnetic properties, Ag₂S addition results in comparatively less suppression of the superconducting transition temperature in YBa₂Cu₃O_7−δ.</p>