The in situ growth of SnO₂ nanoparticles on graphene have been achieved via a hydrothermal method and the nanocomposites were used as an efficient catalyst for the epoxidation of alkenes with aqueous hydrogen peroxide in nitrile based systems for the first time. Furthermore, the SnO₂/graphene nanocomposites could be readily recovered and reused for at least ten consecutive cycles without significant loss of activity and selectivity.