The primary goal of this work is to explore the possibility of using environmentally benign solvent in a liquid membrane setup in order to separate hexavalent chromium from industrial effluent and perform experimental optimization of its parameters for maximum performance. Vegetable oils have been used for this purpose as they have the capability of extracting heavy metals and they are well known for their biodegradability too. Additionally an extractant n-methyl-n,n,n,trioctylammonium chloride (a.k.a. aliquat 336) has been used to enhance the efficiency of separation as it showed very good carrier property for transport of Cr(VI). Di-sodium ethylene-di-amine-tetra-acetic acid (or Na-2-EDTA) was selected as stripping agent for its affinity towards metal. The efficiency is affected by various physico-chemical parameters which have been optimized for best transport of solute. An initial two-phase study followed by elaborate three-phase bulk liquid membrane study were confirmed by critically more industry-friendly supported liquid membrane study. The prime physico-chemical parameters affecting the system performance were identified for experimental optimization through response surface methodology using central composite design rule. A regression model along with analysis of variance evaluates whether the chosen parameters were of good agreement with experimental results. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.