A simple and rapid extraction method for lead and cadmium with a new reagent 4-(4-chlorophenyl)-2-phenyl-5-thiazoleacetic acid (HCPTA) in n-butyl acetate and their subsequent determination by flame atomic absorption spectrometry has been investigated. The quantitative extraction was observed at pH 8.4. The stoichiometric composition of the extracted species was formulated as M(CPTA)(2), where M = Pb or Cd. The extraction constant (log K-ex) of lead and cadmium were found to be -9.7 +/- 0.11 and -10.44 +/- 0.11, respectively. The effect of various anions and cations on the extraction of lead and cadmium has also been studied. The mutual separation of lead and cadmium has also been proposed. The developed procedure was applied to the determination of these metals in seawater, IAEA (SRM) of soil-7, and copepod-MA-A-1. Higher preconcentration factors can be achieved by using a higher aqueous-to-organic phase ratio.