Abstract The chemical transport of CoCr 2O 4 and NiCr 2O 4 with chlorine as a transport agent has been investigated. On the basis of thermodynamic analysis of the transport reactions at 800–1500 K it has been established that the gas phase should contain Cl 2, CrO 2Cl 2 and CoCl 2 during transport of CoCr 2O 4, while Cl 2, CrO 2Cl 2 and NiCl 2 should be present when NiCr 2O 4 is transported. Within the same temperature range cobalt chromite should be transported without decomposition whereas nickel chromite would probably decompose at high temperatures and a low total pressure in the transport system. Octahedral single crystals of CoCr 2O 4 with a spinel structure have been obtained whereas NiCr 2O 4 formed octahedra and plates with a tetragonal structure. The reasons of the differences observed with the systems CoCr 2O 4 Cl 2 and NiCr 2O 4 Cl 2 have been discussed.