The process flowsheet for a soybean oil electrohydrogenation plant has been devised and heat and mass balance calculations on unit operations equipment were performed using a commercially available process simulation software package (PRO/II from Simulation Sciences, Inc.). The design and anticipated performance (current efficiency and power requirements) of the electrochemical flow cells were based on a laboratory-scale radial-flow-through Raney nickel powder electrocatalytic hydrogenation reactor. A semiempirical porous electrode model, that reproduced laboratory-scale reactor data, was incorporated into the PRO/II software as a unit operations subroutine module. Operation of a 3.0 x 10(6) kg y(-1) electrochemical plant was simulated on a computer for different soybean oil/electrolyte feeds and reactor current densities. Based on the PRO/II results, an economic analysis of the process, including capital, installation and operating costs of all equipment was carried out. The lowest total production cost for a brush hydrogenation oil product (20% reduction in the number of double bonds) was obtained at a current density of 15 mA cm(-2) and a feed composition of 10 wt:vol % soybean oil in solvent/supporting electrolyte (US$ 0.13 kg(-1) for an assumed five year straight line depreciation of capital equipment). This cost was higher than that for a comparable-size chemical catalytic soybean oil hydrogenation plant (US$ 0.019 kg(-1)). When the cost of the soybean oil starting material (US$ 0.68 kg(-1)) was factored into the economic analysis, the production plus raw material cost of the electrocatalytic process was only 16% greater than that for the chemical catalytic plant. The production cost for the electrosynthesized hydro-oil product may be tolerable because the oil has a high nutritional value (a lower trans isomers content) which may command a higher selling price.