Abstract: A high-pressure liquid chromatography (HPLG) technique for determination of partition coefficient (P) was investigated. Favourable result was obtained using a permaphase ODS column with reversed-phase systems methanol-water and acetic acidwater. Log P correlates linearly with log k' for a number of standards. The partition coefficient of a series of radioprotective cinnamic acids and related compounds have also been determined. The method is rapid, reproducible and simple. The experimental data of these compounds coincide with the value calculated by the Hansch method with a deviation less than 10%.