Determination of the structure and solvation states of organolithium aggregates in complex solution remains a challenging task. Here, we show that (1)H Pure Shift DOSY NMR provides better resolution spectra without overlapping, even for complex solutions of mixed aggregates of n-BuLi/n-BuOLi. This ensures the direct observation of the apparent diffusion constant for each component in the solution and therefore allows a fast assignment of aggregation states, and solvation degree.