Four In(III) xanthate complexes, [In(S2COR)3] where R = Me, Et, iPr and sBu, respectively, were synthesized, characterized and subsequently used as single source molecular precursors via a solventless thermolysis route to obtain indium sulfide materials. By choice of precursor and reaction temperature crystalline powders of tetragonal In2S3, cubic In2S3 and cubic In2.77S4 were acquired. The phase identification and purity were conducted through examination of the experimental powder X‐ray diffraction patterns relative to the simulated patterns for single X‐ray crystal diffraction.