This dataset includes lignin phenol monomer concentrations normalized to 100 mg of organic carbon. These analyses were conducted on select intervals from peat cores collected at the Alligator River (AR) and Great Dismal Swamp (GDS) National Wildlife Refuges in North Carolina and Virginia/North Carolina, USA, respectively. The eight lignin phenol monomers provide unique proxy information on the source, character, and state of decomposition of soil organic matter. Peat cores from the GDS were collected from three main forest communities; pocosin (POC; dominated by pond pine in the canopy and shrubs), Atlantic white cedar (AWC: called CDR to differentiate from the AR cores), and red maple-black gum (MPL). The GDS has been subject to intensive drainage and selective removal of AWC over the last two centuries. In contrast, the AR site represents an intact, undrained stand of AWC, a coastal plain wetland ecotype that has become increasingly rare on the east coast of the U.S. The contrast enabled us to assess the carbon chemistry of GDS peats, including the decomposition status as a result of these long-term disturbances. There are two files in this dataset: 1) a comma delimited machine-readable file (.csv) that represents the data dictionary, and 2) a comma delimited machine-readable file (.csv) containing the data.