Silicone-epoxy resins were synthesized through hydrosilylation of 1,2-epoxy-4-vinyl-cyclohexane with 1,3,5,7-tetramethycyclotetrasiloxane. The silicone-epoxy resins showed high reactivity in the presence of aluminum complex/silanol compound catalysts. Curing of the resins was effected at extremely low concentrations of the aluminum acetylacetonate/Ph2Si(OH)(2) catalyst to give hard materials with optical clarity. For the silicone-epoxy resins containing Si-H bonds, Al(acac)(3) alone is effective for the curing. The cured silicone-epoxy resins showed excellent UV resistance. An improvement in the lifetime of UV-LEDs was achieved using the silicme-epoxy compositions as encapsulant. (C) 2007 Wiley Periodicals, Inc.