Ultrahigh-resolution Fourier transform tandem mass spectrometry was employed to reveal novel structural detail of the natural complex mixture dissolved organic matter (DOM) that is found ubiquitously in soils and rivers. We developed and evaluated a novel approach to decipher the structural detail that is encrypted in DOM. A DOM sample from a spruce forest (Wetzstein, Germany, 50° 27' 13" N; 11° 27' 27" E; 785 meter above sea level) was used as a representative biodegraded DOM mixture of high complexity and measured by direct-injection tandem mass spectrometry (DI-ESI-Orbitrap-MS/MS). The unknowns in DOM were then compared with indicative tandem MS features (mass differences, "Δm" features) from known standard compounds (14 phenolic standard substances measured in parallel, and 11280 library mass spectra available from the java-based software framework SIRIUS) and natural product and in-silico structure suggestions. The dataset consists of six subsets (Data Set ds01 - ds06), all of which are xlsx files.