Abstract: A method was developed for the quantitative determination of weak organic acids in coal tar by means of potentiometric titration using KOH solution as a titrant and N, N- dimethylformamide as a solvent. The end point of the titration is clearly determined by the inflections of the curves at the equivalence points. Modifications were suggested for GB7304 method, which is unable to get acid number in coal tar sample. The modified method was successfully applied to analyze the coal tar samples. The standard addition recovery is 96%-105%, with RSD’s (n=5) in the range of 0.4%-1.1%.