The widely used cone penetration test (CPT) allows in-situ measurements of soil behaviour during continuous penetration. The traditional sensors incorporated in a cone penetrometer are for measuring cone resistance, sleeve friction, pore pressure, and inclination. Many supplementary sensors have been studied and tried in research settings and in practice. Examples are sensors for natural gamma radiation, electrical resistivity and time domain reflectometry. None have made it to routine practice. As an introduction to the thermal cone penetration test, this thesis presents a review of CPT add-on sensors that (1) allow continuous penetration at 20 mm/s, (2) considered robust, i.e. have no external moving parts, (3) offer potential for broad geotechnical value, i.e. not limited to special applications only. The review considers recent advances in electronics, sensor technology, and data processing systems. The Thermal Cone Penetration test (T-CPT) was introduced by Akrouch (2016) using temperature decay test to determine the soil thermal conductivity. An improved interpretation model was proposed by Vardon (2018) and validated via an in-situ testing programme (Vardon et al., 2018). The T-CPT records temperature variations during continuous penetration depending on different factors such as soil type (grain size), soil strength, and thermal properties of soils. In this report, the potentials of the thermal cone penetration test prototype developed and used by Fugro are investigated during continuous penetration conditions in order to determine the possible dependencies between the soil engineering properties and the T-CPT measurements.