Crude oil is a mixture of hydrocarbons, dispersed water droplets, salt, and sediment in a continuous oil phase. Presence of natural surfactants, and applied drag forces on the dispersed water during the oil production, form a stable water-in oil emulsion. Although many demulsifier agents have been developed to break the crude oil emulsion, economic and environmental problems have limited their application. In this research, cellulose-based compounds are used as demulsifier due to their unique properties. They are biodegradable, non-toxic, and environmentally friendly. The efficiency of alpha-cellulose, microcrystalline cellulose, ethylcellulose at different viscosity grades, and the mixture of ethylcellulose and ethoxylated coco amine are investigated to break the crude oil emulsion through bottle test. According to the experimental data, although ethylcellulose is efficient to break emulsion, low dehydration rate is the main disadvantage of that agent. Moreover, to achieve the maximum dehydration capacity and rate, the optimal demulsifier formulation is obtained based on the experimental results. Finally, the effect of temperature, agent composition, and demulsifier concentration are evaluated on the dehydration capacity and rate of selected agents. The results show that the mixture containing ethylcellulose 46 mPa s and ethoxylated coco amine presents the higher dehydration rate and capacity. (C) 2017 Elsevier B.V. All rights reserved.