A technique for the removal of quinoline insolubles (QI) and ash in coal tar pitch (CTP) using a high-voltage electrostatic field (EF) was developed. QI and ash removal were carried out under an electrical field strength of 2.25 x 10(5) V/m and a temperature of 35 degrees C with oil washing as the solvent. The results showed that QI and ash can be deposited onto cathodes under optimal conditions. CTP obtained via the proposed treatment was QI-free and of low ash content. For comparison, QI removal using the centrifugal method (CM) was also performed. The deposits on the cathode were analyzed using X-ray diffraction and thermal analysis. The findings confirmed that the products obtained through EF and CM have very similar features. However, the energy consumption of EF during QI and ash removal was only one-twelfth that of CM. The proposed technique may be easily implemented in the industry scale and the deposits could be conveniently cleared from the cathode. (C) 2012 Elsevier Ltd. All rights reserved.