Combinatorial Chemistry and High-Speed Experimentation techniques find a growing number of applications in catalysis. Here, these techniques have been applied to the optimisation of the different steps in the preparation of active titanium silsesquioxane catalysts for the epoxidation of alkenes. First, the synthesis of the silsesquioxane precursors was optimised. The best precursor was obtained by the hydrolytic condensation of cyclopentyltrichlorosilane in acetonitrile. This lead was characterised by Si-29 NMR Spectroscopy and by Mass Spectrometry. Next, the effect of the nature of the titanium centres bound to the silsesquioxane structures on the catalytic activity was explored. The coordination of diols to the titanium centres resulted in an improvement of the activity when using H2O2 as the oxidant. (C) 2003 Elsevier Science B.V. All rights reserved.