This review article is devoted to the discoveries and/or knowledge developed in the past 10 years in the area of catalytic liquid-phase oxidation with hydrogen peroxide on mesoporous molecular sieves of MCM-41 type modified with various transition metals. The following parameters influencing activity and selectivity of the catalysts are considered: (i) nature of matrix for metal species limiting diffusion effects; (ii) isolation of metals; (iii) hydrophobicity of catalysts; (iv) nature of solvent; (v) reducibility of metal species; (vi) leaching of metal from the solid. Advantages and disadvantages of MCM-41 materials are pointed out in relation to the properties of TS-1 and TS-2 zeolites. (C) 2004 Elsevier B.V. All rights reserved.