The epoxidation of a variety of electron-deficient alpha, beta-unsaturated carbonyl compounds has been studied using dilute H2O2 and titanium-containing zeolites under liquid-phase conditions. The influence of the reaction medium and the structure of titanium-containing silicates (Ti-beta(OH), Ti-Al-beta(OH), Ti-beta(F), TS-1, TS-2, Ti-MCM-22, and Ti-MCM-41) have been investigated. The weak basic acetonitrile solvent shows better activity and selectivity for epoxide than for other solvents used in this reaction over large-pore zeolite Ti-beta. Among the various titanosilicates studied, aluminum-free Ti-beta exhibits the best activity and H2O2 selectivity for cyclic alpha,beta-unsaturated ketone, whereas Ti-beta and TS-1 exhibit similar activities for open-chain alpha,beta-unsaturated carbonyl compounds. The medium-pore TS-1, TS-2, and Ti-MCM-22 exhibit lower activities for the oxidation of cyclic ketones due to their diffusion limitation. For unsaturated ketones, epoxides are selectively formed, whereas unsaturated aldehydes mainly produce carboxylic acid. Branching at alpha-and/or beta-carbon influences the reactivity of the carbonyl compounds considerably. However, the Ti-beta/H2O2 catalytic system fails to oxidize substrates like alpha,beta-unsaturated acids, alpha,beta-unsaturated esters, and isophorone.