[en] A time-resolved method for the study of structure and spin dynamics of transient radicals in liquids is described. Pulsed electron beam or pulsed laser irradiation is used to create transient radicals in solution. Irradiation is carried out in the field of a variable electromagnet, and the diamagnetic products are transferred rapidly using a fast flow system to an NMR probe. During the radical reaction, a 0.5 to 10 μs rf pulse is applied to the reacting sample at an appropriate frequency, corresponding to a nuclear energy level spacing of the given radical. Nuclear spin level population changes in the radical are transferred to its reaction product and detected as intensity changes in their NMR spectra. The method is illustrated using radiolyzed sodium malonate