The oxidative cleavage of trans-1,2-cyclohexanediol to adipic acid was studied with hydrogen peroxide as oxidant and titanium-containing Y zeolites as catalysts. These materials were obtained by treating zeolite Y with ammonium hexafluorotitanate. Selectivities of up to 80% could be achieved at conversions of 50%. The catalysts could be reused several times without activity loss. The titanation of Y zeolites is reproducible. Independently prepared Ti-Y zeolites lead to the same catalytic results. Titanium is present as a species that causes a UV-VIS band at 260 nm. Bands indicating anatase or rutile were not observed. No leaching of titanium was detected. The presence of mesopores in the catalyst structure increases the conversion. Through variation of process parameters like temperature and reactant/catalyst ratio, the undesired decomposition of the hydrogen peroxide can be partially suppressed. In comparison, cyclohexene oxide is cleaved with selectivities similar to those of trans-1,2-cyclohexanediol. By contrast, cyclohexanol and cyclooctene oxide are unselectively oxidized. Diffusion constraints seem to play a decisive role.