A new method for the preparation of sulfur (S) doped iron (Fe) samples is presented. The required amount of S in Fe is obtained by allowing the vaporized form of S to diffuse into a Fe sample (10 mm diameter, 0.5 mm thick) kept at a temperature of 750 K. Depth profile analysis using Auger Electron Spectroscopy and Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF‐SIMS) showed that the method is reproducible and can be used for the preparation of samples with different S concentrations. It was also found that S deposited onto Fe forms the desired FeS phase, which will prevent S from evaporating when the sample is annealed. Prepared samples were annealed to obtain homogeneity of S in Fe, after which the amount of S in the respective samples was determined by quantitative TOF‐SIMS. The outcome of the results suggests the application of this method to other high melting point host and low melting point dopant systems. Copyright © 2014 John Wiley & Sons, Ltd.