Hydrogenolysis of 1,1a,6,10b-tetrahydro-1,6-methanodibenzo[a,e]cyclopropa[c]-cycloheptene over Ru-embedded colloids is reported. The preparation of the catalysts was made by embedding pre-synthesized Ru-stabilized colloids in a zirconia or silica sol-gel matrix. N+(C8H17)(4)Br- and N+(CH3)(3)C16H33Br- were used as stabilizers. The catalysts were characterized by adsorption-desorption isotherms of N-2 at 77 K, H-2-chemisorption, XRD, small angle scattering (SAXS) and XPS. The reaction was found to be mainly influenced by the catalysts characteristics (nature of the inorganic matrix and metal dispersion) and by the reaction conditions (merely the temperature and the solvent). The first step, namely the fission of the cyclopropane ring, proceeds regioselectively. (C) 2002 Elsevier Science B.V. All rights reserved.