The effect of the modifier 1-decanol on the extraction of tartaric acid by the extractants tri-n-octylamine (TOA), quaternary ammonium chloride (Aliquat 336), or their mixture in the diluent n-dodecane was studied at different pH values. The effect of the modifier was examined as a function of the initial pH value of the aqueous solution for the three extractants mentioned above. A positive, negative, or no effect of the modifier on the distribution coefficient of tartaric acid was observed in the different cases.