This contribution introduces a strategy to use Ru(II)-porphyrin complexes as catalysts for the epoxidation of alkenes in water. The design is based on shell cross-linked micelle-based nanoreactors with hydrophobic cores and hydrophilic shells as supports for the Ru(II) porphyrin complexes. The supported complexes are efficient catalysts for oxidation reactions, specifically the selectively oxidation of alkenes to epoxides. The presented strategy is the first system that allows for running Ru-catalyzed epoxidation reactions in water. (C) 2016 Elsevier B.V. All rights reserved.