The compound [C 4 H 12 N 2 ][CoCl 4 ] was ionothermally synthesised in an ionic liquid medium and shown by X-ray single crystal diffraction analysis to consist of four piperazinium C 4 H 12 N 2 2+ cations and four CoCl 4 2- complex anions. Thermogravimetric analysis indicated that [C 4 H 12 N 2 ][CoCl 4 ] possesses good thermal stability below 320 °C.