The properties and performance of an O-2-H-2 system used for the direct oxidation of olefins have been studied on the example of direct oxidation of propylene. Ti-catalysts modified by impregnation with palladium tetraminenitrate and platinum tetraminechloride and by followed reduction under various conditions were used as bifunctional catalysts. New investigations showed that the pre-impregnation of the catalyst with salt and the using of alcohols or ketones as solvent for the impregnation of the catalyst with precious metal improved the selectivity of propylene oxide (PO). Also the influence of other precious metals such as Ir or Au as promoters on titanium silicalite-1 (TS-1) has been studied. In addition to propylene, other olefins like styrene or terpenes were also tested in direct oxidation with an O-2-H-2 system by using Pd/PtrTS-1 or Pd/Pt/Ti-MCM-41, respectively. The use of these olefins as substrate lead to low yields of the desired product and showed the limits of the O-2-H-2 oxidation system, so far.