A reactor capable of efficiently collecting kinetic data in flow is presented. Conversion over time data is obtained by passing a discrete reaction slug back-and-forth between two residence coils, with analysis performed each time the solution is passed from one coil to the other. In combination with minimal material consumption, this represents an improvement in efficiency for typical kinetic experimentation in batch as well. Application to kinetic analysis of a wide variety of transformations is demonstrated, highlighting both the versatility of the reactor and the benefits of performing kinetic analysis as a routine part of reaction optimization/development. Extension to the monitoring of multiple reactions simultaneously is also realized by operating the reactor with multiple reaction slugs at the same time.