In recent years, the study of the Thermo-Hydro -Mechanical (THM) behaviour of geomaterials has become a growing area in geotechnical engineering due to the increasing interest in energy geostructures and underground nuclear waste disposal. Advanced laboratory testing is essential in gaining an understanding of the THM behaviour of soils and solving these complex geomechanical problems. This paper describes the development of a new triaxial apparatus at the Imperial College Geotechnics Laboratory, capable of testing saturated soils at temperatures up to 85°C and pressures up to 800kPa. In order to aid its design, numerical analysis of the thermal response of the cell was conducted using the Imperial College Finite Element Program (ICFEP) with its newly developed THM capabilities.