The influence of Sn on the enhancement of critical current densities, Jc, in the bulk samples of PbMo₆S₈ has been systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), AC susceptibility, and specific heat experiments. The results indicate that the addition of Sn, as an adjunction (dopant) or as a substitution, has a considerable effect on the structural, superconducting, microstructural and grain boundary properties. The observed increase in Jc is discussed in terms of improved interconnectivity between the grains, better homogeneity of the samples, and, more importantly, lower grain boundary contamination.