Infrared spectroscope study on reactive extraction of Cephalosporin-C (CPC) and 6-Aminopenicillanic acid (6-APA) with secondary and tertiary amines and a quaternary amine salt as the extractants in butyl acetate as the diluent has been reported. The study aims at analysing the chemical interaction involved in the complexation of the molecules with the extractant and the reaction stoichiometry. Amberlite LA-2, Trioctylamine and Aliquat-336 (Tricaprylyl methyl ammonium chloride) were used as the extractants. The results of experimental extraction equilibrium study and spectroscopic analysis indicate the formation of (1:1) complex via ion-exchange reaction of CPC and B-APA with Aliquat-336. The ion-pair extraction with Amberlite LA-2 and Trioctylamine exhibited non-stoichiometric complexation in accordance with experimental observation on equilibrium relationship.