Various types of vegetable oil-based organic solvents (VOS), i.e. vegetable oils (corn, canola, sunflower and soybean oils) with and without extractants (di-2-ethylhexylphosphoric acid (D2EHPA) and tributylphosphate (TBP)), were investigated into their potentiality as greener substitutes for the conventional petroleum-based organic solvents to extract Cu(II) from aqueous solutions. The pH-extraction isotherms of Cu(II) using various vegetable oils loaded with both D2EHPA and TBP were investigated and the percentage extraction (%E) of Cu(II) achieved by different types of VOS was determined. Vegetable oils without extractants and those loaded with TBP alone showed a poor extractability for Cu(II). Vegetable oils loaded with both D2EHPA and TBP were found to be the most effective VOS for Cu(II) extraction and, thus, are potential greener substitutes for the conventional petroleum-based organic solvents. (C) 2010 Elsevier B.V. All rights reserved.