The kinetics of the reaction of ninhydrin and DL-tryptophan has been carried out in TX-100 micellar media at 40°C and pH 5.0 (sodium acetate-acetic acid buffer). The reaction rate increased with increase in [TX-100] and the rate constant - [surfactatant] data are analysed using the modified Menger and Portnoy pseudo-phase model. The rate constant in the micellar medium (Km) and micelle binding constants of ninhydrin (KN) aid DL-tryptophan (KS) are evaluated.