This study is aimed to develop and evaluate extractive crystallization processes for separating 2,6-dimethylnaphthalene, a starting material for high performance engineering plastics and liquid crystallization polymers, from 2,7-dimethylnaphthalene. At first, the solubility of 2,6-dimethylnaphthalene and 2,7-dimethylnaphthalene in three solvents, i.e. ethyl acetate, ethanol, and hexane, was studied. Secondly, two extractive crystallization processes, called process I and process 2, for separating 2.6-dimethylnaphthalene and 2,7-dimethyl naphthalene were developed and evaluated based on equipment and operating costs. The processes developed fractionate 2,6-dimethylnaphthalene and 2,7-dimethylnaphthalene into pure components with yields of 100% by involving dissolution, crystallization, evaporation, and filtration. It was found that the larger the difference of hot and cold temperatures. the lower the capital and operating costs. Process I was found to be the best when hexane is used as solvent, on the other hand, process 2 was found to be the best when ethyl acetate is used as solvent. Lower costs were observed when 2.6-dimethylnaphthalene is removed from the first filter. Under the studied condition, process 2, with ethyl acetate as solvent and operates at hot and cold temperatures of 50 and 35 degreesC, respectively, was found to be the best alternative. Further studies are necessary to find out if the processes developed are more economic than the other separation processes. (C) 2003 Elsevier B.V. All rights reserved.