Radio-frequency muon spin resonance is a powerful technique for studying free radicals and their reaction kinetics, but it has not yet been used to study complex reactions in solution in which multiple reaction pathways are available. The C6H6Mu radical (formed by Mu addition to benzene) can react with a stable free radical like DPPH in two ways; spin-exchange or chemical termination. RF-muSR will be used to study the C6H6Mu + DPPH reaction and measure the rates of the two reaction pathways, and the overall reaction rate. The rate constants will be measured either by the evolution of the muon polarisation on resonance or with delayed RF pulses. The overall rate will be determined from the disappearance of C6H6Mu, the chemical termination rate from the build-up of diamagnetic products, and the spin exchange rate is the difference between the overall and chemical termination rates.