We designed solid catalysts for liquid-phase epoxidation based on functionalized silica -Si(CH2)(3)Q(+) [Q: -NH3, -NEt3, -NC5H5, -PPh3] and [HPO4{W2O2(mu-O-2)(2)(O-2)(2))](2-). The approach that we adopted allowed us to avoid the use of chlorocarbon solvent and enabled catalyst recycling. By using supports with 4 different linking chains between the anion and silica and different surface lipophilicities, we followed their influence on catalyst activity in the epoxidation of cyclooctene and (R)-limonene by H2O2 in t-BuOH. All solids were active in cyclooctene epoxidation (conversion up to 100%; epoxide selectivity 100%; TOF 2-4 h(-1) anion(-1)). The degree of surface coverage by organic functions was crucial for recycling performance. Catalysts with low densities of organic functions and hydrophilic surfaces were easily deactivated. End-capping improved their stability but decreased their activity. Catalysts with dense coverage of onium groups and the active site in a hydrophobic chloropropyl environment demonstrated high activity and excellent recycling stability. Less promising results were obtained in the epoxidation of (R)-limonene. (C) 2007 Elsevier Inc. All rights reserved.