A novel real-time method was developed to evaluate the bisphenol A degradation kinetics by molecular ozone and radical pathway using the stopped-flow technique. The second-order kinetics was determined under pseudo-first-order conditions for the molecular pathway by the absolute rate constant method and for the radical pathway by the R-ct concept involving the hydroxyl radical and ozone ratio. Bisphenol A degradation by ozone was performed and evaluated at a pH ranging from 2 to 10. At pH<4 (molecular pathway), the second-order rate constant value was 1.12x10(4)M(-1)s(-1) and for the radical pathway at pH>10, the constant was 3.43x10(9)M(-1)s(-1). To validate the method, ciprofloxacin degradation kinetics was determined at pH 8 by radical pathway, in 4.55x10(9)M(-1)s(-1). The method permits the determination of kinetic parameters for the design of chemical reactors; avoiding the generation of undesirable reactions and by-products in the degradation of emerging compounds.