Conformational transitions (refolding) between long-lived conformational states constitute the time-limiting step during the folding process of large RNAs. As the dynamics of these reactions dominate the regulatory and other functional behavior of RNA molecules, it is of importance to characterize them with high spatial and temporal resolution. Here, we describe a method for the investigation of RNA refolding reactions based on the photolytic generation of preselected conformations in a non-equilibrium state, followed by the observation of the folding trajectory with real-time NMR spectroscopy.