The voltammetric behavior of 4-methyl-N-8-quinolinybentenesulfonamide, closely related to the active component of the commercial extractant LM 34, has been studied in 0.1 M KC1/2j% methanol medium as a function of pH, using polarography and cyclic voltammetry techniques. The electrochemical behavior of the extractant in the presence of Cu (11) ions has also been described. The commercial LLX 34 product exhibits a similar behavior both in differential pulse polarography and cyclic voltammetry, and polarographic determination methods have been developed for both reagents. The relationship between reduction peak current and concentration is linear up to 1.96 X M for 4-methyl-N-8-quinolinylbenzenesulfonamide, and the corresponding function for LIX 34 indicates a low percentage of the active component in the commercial extractant.