A moisture curable composition capable of cure to an elastomeric body, the composition comprising (a) an organopolysiloxane having not less than two silicon-bonded hydroxyl or hydrolyzable groups; (b) a silane of the general formula G.sub.2-Si--R.sup.1.sub.2, wherein each group is reactable with the hydroxyl or hydrolyzable groups in (a), and each R.sup.1 group is an alkyl group having from 1 to 10 carbon atoms, an alkenyl group, an alkynyl group an aryl group or a fluorinated alkyl group; (c) one or more fillers and (d) a photocatalyst. Preferably at least one R.sup.1 group is unsaturated, but in the absence of this there is provided an additional component in the form of (e) an unsaturated compound selected from the group of an unsaturated short chain siloxane, an unsaturated cyclic siloxane, an unsaturated fatty acid an unsaturated fatty alcohol or an unsaturated fatty acid ester. The cured product is generally used as a sealant, which avoids dirt pick-up after cure and has a protective layer on the sealant interface with air.