Stibnite is the principal sulfide mineral and the most important ore mineral in antimony deposits worldwide. In situ S and Sb isotope analyses of stibnite are crucial for investigating the genesis of antimony deposits and for deciphering detailed mineralization processes. To obtain reliable in-situ isotopic data, matrix-matched reference materials are essential for correcting instrumental mass fractionation. In this study, two natural stibnite samples (WX34-80 and KKY) were characterized on the basis of their elemental and isotopic compositions. The results demonstrate that both samples are homogeneous in terms of S and Sb contents, as well as their isotopic signatures, and exhibit significantly distinct sulfur isotopic compositions, rendering them highly suitable reference standards for in situ Sb and S isotope analyse using LA-MC-ICP-MS. Based on IRMS measurements, the recommended δ3?SV-CDT values are ?2.17 ± 0.29‰ (2SD, n = 18) for WX34-80 and 10.63 ± 0.38‰ (2SD, n = 18) for KKY. Correspondingly, SN-MC-ICP-MS analyses yield recommended δ123Sbspex values of ?0.33 ± 0.07‰ (2SD, n = 8) for WX34-80 and ?0.29 ± 0.05‰ (2SD, n = 8) for KKY.