A highly sensitive and selective method for the determination of valproic acid salts in pharmaceutical tablet formulations by a high performance liquid chromatography method with coulometric electrochemical detection is described. The precolumn derivatizations of valproic acid and the internal standard (n-hexanoic acid) were carried out using 1-(2,5-dihydroxyphenyl)-2-bromoethanone as an electroactive labeling reagent. The resulting electroactive esters were separated by isocratic elution of a 3 μm Adsorbosphere ODS column with methanolacetonitrile-acetate buffer eluent.