This dataset contains raw experimental triaxial testing data as outlined in "Castagna, A., Ougier‐Simonin, A., Benson, P. M., Browning, J., Walker, R. J., Fazio, M., & Vinciguerra, S. (2018). Thermal damage and pore pressure effects of the Brittle‐Ductile transition in Comiso limestone. Journal of Geophysical Research: Solid Earth, 123(9), 7644-7660.s, http://dx.doi.org/10.1029/2017JB015105". The data is provided in a .zip folder containing the files of 16 experiments that are accompanied by a README file for introduction. Files format is Microsoft Excel Worksheet (.xlsx) and data are tabulated. Each file contains the corresponding relevant sample’s details, and each column of data is clearly labelled, units included. For each experiment, time, radial and axial pumps volume displacements and pressures, top and bottom pore fluid pumps volume displacements and pressures, internal temperature, LVDT signals were recorded. Twenty right cylindrical samples of ‘Comiso’ limestone (Ragusa Formation; Sicily) were tested in triaxial compression at a range of confining pressures simulating depths of 290 m, 620 m, 1.2 km, and 2.0 km respectively, assuming an average density of the over-burden load of 2470 kg/m3. Prior to strength test, each sample was either oven dried (ca. 12 hours at 85 °C followed by cooling in a desiccator for 1 hour) or water saturated (samples in distilled water under vacuum for 24 hours). A subset of these samples has also been thermally treated at 150, 300, 450 and 600oC to induce thermal cracking prior to the mechanical testing. All tests were conducted at 10-5 s-1 axial strain rate in assumed drained conditions when relevant, and at room temperature. For saturated tests, the initial loading was applied in two steps, first by increasing Pc hydrostatically (σ1=σ2=σ3) until the desired confining pressure was reached, and then introducing pore fluid pressure, as per the functionality of the experimental set-up. The experiments were conducted by Drs A. Castagna, M. Fazio and P. Benson using the Snachez triaxial cell at the Rock Mechanics Laboratory of the University of Portsmouth. All responsible for the collection and initial interpretation of the data. Only 17 experiments are reported in this set of data; the missing 3 datasets are believed to be only available on the local computer storage of the triaxial apparatus used at that time.