Abstract: BACKGROUND: Among the polyols, 1,3 diols are selective and efficient extractants for boron but significant solubility of these into aqueous solutions restricts their application in large scale separation processes. Solvent modifiers can be used to reduce extractant loss to the aqueous phase. Efficiency of the diolic extractants for boron separation have been tested in the presence of different solvent modifiers. RESULTS: Compared with other modifiers studied, decanol gives better stability to diolic molecules in the Kerosene phase and exhibits a reduced negative effect on the extraction of boron. Next to decanol, the low viscous 2,6-dimethyl-4-heptanone can be used as solvent modifier. In successive extraction studies, 2-butyl-2-ethyl-1,3-propanediol (BEPD) showed better stability among the diols studied in the presence of decanol in the organic phase. CONCLUSION: Quantitative removal of boron was achieved from industrial waste solutions such as a spent phosphate passivation bath and a cutting fluid, using 0.6 mol L-1 BEPD and 0.6 mol L-1 2,2,4-trimethyl-1,3-pentanediol (TMPD) in 25% decanol/Kerosene organic phase