The low-temperature reactions of H2S (0.2-500 ppm) with Cu2O and a group of copper(I) complexes have been studied. [Cu(OAc)](n) Cu-4(OCOCF3)(4)(C6H6)(2), and Cu(hfac)L where hfac = hexafluoropentanedionate and L = 1,5-cyclooctadiene (COD) or diphenylacetylene reacted rapidly and quantitatively. Cu-2(hfac)(2)LL where LL = cyclooctatetraene or norbornadiene and [Cu(OCOC6H5](4) reacted slowly or not at all. Rapid and quantitative conversion is apparently enabled by the displacement of ligands of large molar volume resulting in a porous Cu2S product. Cu(hfac)(COD) is nonporous, and quantitative studies were carried out in a packed-bed reactor for three size ranges of particles. The initial rate is first order in H2S and, according to an approximate estimate, appears to be dependent on the external surface area of the particles. The rates of reaction were faster than those of commonly used absorbents, while the stoichiometric conversion is unusual. Such properties suggest applications in gas cleanup and chemical analysis of H2S.