Higher order derivative techniques are mainly used in deconvoluting the overlapping absorption spectra of various analytes in their determination. The procedure utilizing higher order derivatives in molecular absorption spectrophotometry essentially are based on the formation of either binary or ternary complex formation. This paper deals with fourth order derivative spectrophotometric procedure for the determination of traces of lead based on the liquid-liquid extraction of ternary ion association complex lead with 1,10-phenanthroline and rose bengal into chloroform. The ternary ion associate is stable for over 24 hours. The developed procedure is simple, rapid, reliable and allows the determination of as low as 20 ppb of lead in sea water samples.