Abstract Predicting the association of contaminants with both particulate and dissolved organic matter is critical in determining the fate and bioavailability of chemicals in environmental risk assessment. To date, the association of a contaminant to particulate organic matter is considered in many multimedia transport models, but the effect of dissolved organic matter is typically ignored due to a lack of either reliable models or experimental data. The partition coefficient to dissolved organic carbon (KDOC) may be used to estimate the fraction of a contaminant that is associated with dissolved organic matter. Models relating KDOC to the octanol–water partition coefficient (KOW) have not been successful for many types of dissolved organic carbon in the environment. Instead, linear solvation energy relationships are proposed to model the association of chemicals with dissolved organic matter. However, more chemically diverse KDOC data are needed to produce a more robust model. For humic acid dissolved organic carbon, the linear solvation energy relationship predicts log KDOC with a root mean square error of 0.43. Environ. Toxicol. Chem. 2011;30:2023–2029. © 2011 SETAC