This dataset contains raw experimental direct shear testing data as presented by "Ougier-Simonin, A., Castagna, A., Benson, P. and Walker, R. (2017). Direct shear characterisation of simulated clay-bearing gouges: a case study from the Pernicana Fault System (Mount Etna, Sicily). In EGU 2017 General Assembly Conference Abstracts (p. 15794)". The data is provided in a .zip folder containing the files of 12 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, axial force, axial displacement, axial stress, confining displacement, confining pressure, internal temperature, and axial delta P were recorded. Details of calculations for shear stress and coefficient of friction are also provided. Twelve gouge (rock powder) samples of Monte Salici sandstone (Numidian Flysch, Appenninic-Maghrebian Chain; Sicily), ‘Comiso’ limestone (Ragusa Formation; Sicily) and Quaternary Clays (blue-grey clay in Fiumefreddo, Sicily) were tested in direct shear using sliding holders in triaxial compression at a range of confining pressures of 10, 30 and 50 MPa. Clay and sandstone samples tests were conducted at 0.3 microns per second of axial displacement rate; limestone and mixed gouges tests were conducted at 1 micron per second. Maximum displacement: ca. 9.8mm. All tests done at room temperature. The experiments were conducted by Drs A. Castagna and A. Ougier-Simonin using the MTS815 Rock Testing System in triaxial configuration and homemade sliding holders in the Rock Mechanics and Physics Laboratory of the British Geological Survey; both responsible for the collection and initial interpretation of the data.