Absorption and desorption are temperature dependent phenomenon. Absorption solvent used in the process, passes through several heating and cooling cycles during the absorption and desorption process. This heating and cooling causes polymerization in many solvents. Therefore, absorptivity of the solvent decreases with time. A detailed analysis of wash oil, used for naphthalene scrubbing in coke oven byproduct plant, is given in this article. This study reports the effect of inlet wash oil temperature in the naphthalene scrubber, on the absorptivity of naphthalene from crude coke oven gas. Naphthalene scrubber and stripper unit of two different byproduct plants are analysed in this article. Basic difference between these two byproduct plant is that the inlet wash oil temperature in these scrubbers are different. This temperature difference causes variation in heating and cooling cycle of the wash oil. As a result, composition, viscosity, initial boiling point of the oil also changes. Rich wash oil and lean wash oil samples were collected from the By Product Plant. Key properties of the oil studied are- density, viscosity, naphthalene content, gas chromatography-mass spectrometry (GC–MS) and ASTM D-86 initial and final boiling point analysis.