The present work deals with the volumetric solvent swelling of the cross-linked macrontolecular organic matter (kerogen) of Estonian kukersite oil shale in binary solvent mixtures. A two-step solvent swelling procedure was used in which swelling was performed first in one solvent followed by the addition of a second solvent. The results confirm the important role of specific interactions in determining the swelling behavior of this kerogen. The kerogen swells more in strong electron donor solvents that are able to break specific kerogen kerogen interaction such as hydrogen bonds. When comparing the maximum swelling achieved, the binary solvent mixtures did not perform any better than strong electron donor solvents, regardless of how the experiments were conducted.