Abstract Single crystals of the magnetic semiconductor CoIn 0.5 Cr 1.5 S 4 , belong to the system CoIn (2‐2X) Cr (2X) S 4 with x = 0.75, was grown by the chemical transport method. X‐ray powder diffraction characterization by the Rietveld method indicated that CoIn 0.5 Cr 1.5 S 4 crystallizes in the space group Fd‐3m, Z = 8, with a = 10.0700(6) Å and V = 1021.2(1) Å 3 , in a normal spinel structure. The temperature dependence of the DC magnetization suggests that the studied compound presents a ferromagnetic behavior with a Curie temperature Tc = 220 K. Sharp spin‐glass like behavior was found also. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)