[en] Pore water that resides in the interconnected pore space between minerals and along grain boundaries in crystalline rocks of low permeability has been extracted successfully by tested laboratory out-diffusion methods using drillcore samples from borehole KR 39 located in the Olkiluoto subarea. The obtained experiment solutions have been characterised chemically and isotopically and related to the in situ pore water composition of the rock. In addition, the method of extraction, together with interfaced measurements of interconnected porosity, provided the opportunity to derive diffusion coefficient values of potential use in predicting future rates of solute transport. Because of the very small volumes of pore water extracted, and the possibility of rock stress release occurring during drilling which might: (a) lead to contamination by drilling fluid, (b) affect the derivation of rock porosity values, and (c) result in input of fluids from ruptured fluid inclusions, great care was taken to avoid such problems or, at least further understand the repercussions. Interpretations of the extracted pore waters are supported by investigations of the rock mineralogy, mineral chemistry, whole-rock chemistry, mineral fluid inclusions, and crush-leach experiments. (orig.)