We have studied the solvation of Th4+ in water, in dimethyl sulfoxide (DMSO), and in their equimolar mixture by using molecular dynamics based on an Amoeba-derived polarizable force field. We have performed an extended structural analysis in order to provide a complete picture of the chemical–physical features of the interaction of Th4+ with the two solvents in their pure and mixed states. Through our simulations we found that, very likely, the first solvation shell in DMSO is not unlike the one found in pure water and contains 9 solvent molecules. The residence time of first shell of DMSO molecules is however much longer than the residence time of water. For the 1:1 mixture we present computational evidence that both water and DMSO participate in the solvation of Th4+ with a slight preference for the latter.