Tensile properties of geomaterials often play an important role in many geotechnical engineering problems. Compacted soil layers in dams, clay liners in landfills, reinforced earth-retaining wall systems, cement stabilized crushed rocks in pavements, etc. are constantly checked for tensile cracking. This type of cracking happens when the developed tensile stress exceeds the tensile strength of the material. Usually, the tensile strength of natural soil is assumed to be negligible. However, it is proven that cement treated soils possess some amount of tensile strength. The determination of tensile strength of cement treated clay, using a newly developed tensile testing apparatus, is focussed in this study. The existence of an optimum cement content for tensile strength is also discussed. © Published under licence by IOP Publishing Ltd.