The thermooxidative stability of blends of a straight-run Jet-A fuel (POSF-2827) and a paraffinic/cycloparaffinic solvent (Exxsol D-80) has been studied in a single-pass tubular heat exchanger operated isothermally at 185 degrees C. Autoxidation of most blends is found to be significantly slower than that of either fuel or solvent. Surface fouling relative to the solvent is increased by addition of jet fuel; this is attributed to reactions of natural antioxidants present in the fuel. Surface fouling relative to the jet fuel is reduced following paraffin addition under conditions of partial O-2 conversion; this is attributed to a lower initiation rate as the concentration of aromatics is reduced. The impact of these findings for mitigation of surface fouling in aircraft fuel lines is discussed.