Molecular dissolved organic matter composition of porewater and water-extractable hot-water Soxhlet extracts. The dataset contains all molecular formulae found with Fourier-transform ion cyclotron resonance mass spectrometry including the respective isotope-free molecular formula, the hydrogen-to-carbon ratio (HC), oxygen-to-carbon ratio (OC), the aromatization index (AImod) and Double bond equivalent (DBE) and the relative intensity in each sample normalized to the total sum of intensities per sample. Samples were analysed with a Electrospray ionisation Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS), Bruker Daltonik GmbH, Bremen, Germany connected to a 15 Tesla superconducting magnet (Bruker Biospin, Wissembourg, France), solariX XR, ICBM-OCEAN (https://rhea.icbm.uni-oldenburg.de/geomol/).