The chemical composition of bronze‐processed Nb3Sn at grain boundaries and its variation as a function of distance from the grain boundary were determined using Auger electron spectroscopy. The composition at the grain boundary was 44.1, 30.6, and 25.4 at. % for Nb, Sn, and Cu, respectively, and approached to the bulk value (∼75 at. % Nb and ∼25 at. % Sn) at ∼20 A˚ into the grain, as determined by a depth‐profiling method.