The datafiles are text files that record the pore fluid pressure, confining pressure, pore volume change, axial force and axial load displacement recorded on the triaxial deformation apparatus during an axial load cycle on a porous rock sample. Each data file represents an individual load cycle from the contact of the loading apparatus to the yield strength, as identified by the user during the experiment. Samples tested included members of the Idaho Gray Sandstone, Mercia Mudstone Group, and lab manufactured synthetic sandstones. The data is associated with submission of the manuscript: 'Porous rock yield strength mapping: single sample probing versus multi-sample conventional measurements.' to the journal Rock Mechanics and Rock Engineering.