Communication: Intercalation into lamellar host lattices is in general poorly understood with regard to mechanistic details. A study is reported here that utilizes energy dispersive X-ray diffraction al a synchrotron source to determine the rats of intercalation of cobaltocene into a range of lamellar metal dichalcogenide lattices. The results are suggested to have general implications for how metallocene intercalation into metal dichalcogenides should be performed in order tit maximize the rate of reaction.