Fouling is a deposit on process equipment. It accounts for a large fraction of the energy loss in the process industries and oil production. This combined experimental and modeling study aims to relate crude oil properties to their intrinsic fouling propensities. By intrinsic it is meant that fouling experiments are conducted without foulant removal by hydrodynamic forces. The fouling behaviors of five crude oils are examined with a laboratory flow unit whose effluent temperatures continuously decline due to buildup of thermal insulating foulant on the wall. A theory is developed based on the premise that fouling is driven by coking reaction and mass transfer. All the complexities of the fouling dynamics can be subsumed in a dimensionless group characterizing fouling rate. The theory predicts the growth rate of foulant thickness. Of 20 oil properties examined, the most influential ones are oil's solvency power and the contents of asphaltenes, basic nitrogen, and metals. These properties are combined into a fouling propensity index that correlates with a fundamentals-based fouling severity index. The resulting fouling property correlation can be used for developing improved fouling reduction methods such as on-line cleaning, blending, and antifouling chemical treatment, to name a few. (C) 2015 Elsevier Ltd. All rights reserved.