Abstract: A room temperature curing composition which cures fast and has good reversion resistance and good package stability is a mixture of 66.75 to 89.4 weight percent of a hydroxyl endblocked polydiorganosiloxane; 5.5 to 10 weight percent of a tetrafunctional ethoxy-ketoximo silane mixture having 6 to 27 weight perent tetraketoximosilane, 9 to 39 weight percent of monoethoxytriketoximosilane, 38 to 60 weight percent of diethoxydiketoximosilane, and 5.5 to 25 weight percent triethoxymonoketoximosilane; 0.1 to 0.25 weight percent of a tin catalyst, 0 to 3 weight percent of an adhesion promoter, and 5 to 20 weight percent of reinforcing silica. These compositions cure to elastomeric materials useful as caulking materials, adhesives, coatings and encapsulating materials for construction and automotive industries.