A nonaqueous potentiometric titration method for the determination of weak acids using ethylenediamine and sodium aminoethoxide as solvent and titrant respectively is discussed. The use of absolutely dry, carbon-dioxide free reagents is found to be essential to accurately determine endpoints. Refinements in purification and storage techniques as well as in experimental procedure compared with earlier work are described in this paper. By using the improved procedures individual phenolic groups in some dihydric phenols were resolved for the first time and previously undifferentiated dihydric phenols are now easily detected and quantitatively determined. In addition, other weakly acidic phenols with previously undetected endpoints have been titrated successfully. The acidic oxygen content of a wide range of Australian coals and of the solid and liquid coal-derived products has been determined by this potentiometric method.