After biodiesel is produced, it needs to be purified very well in order to remove impurities such as soap and glycerin. In the conventional method, washing with water is carried out for purification. However, if this water is not sufficiently removed from the biodiesel, the quality of the fuel produced is adversely affected. In this study, the aim was to remove water from biodiesel produced from sunflower oil and to purify biodiesel in this way. Cationic resin (Dowex HCR-S) was used for purification. The pre-drying and contact time of the resin, the temperature and the amount of resin were selected as parameters. The amount of water adsorbed by the resin was determined for each parameter. According to the results obtained, the parameters in which the maximum amount of water is removed from biodiesel are pre-drying time of 4 h for the resin, contact time of 50 min for the resin, temperature of 15 degrees C and the 6% (by weight) for amount of the resin. At these parameter values, 92.78 wt% of the water in the biodiesel was removed. Also, the water content of biodiesel purified by resin was much less than the maximum value of 500 mg/kg. (C) 2019 Elsevier Ltd. All rights reserved.