One component vulcanizable silicone elastomer compositions contain at least one organosilicon compound bearing a plurality of hydrolyzable groups, optionally one or more crosslinkers bearing hydrolyzable groups, and a catalyst system comprising a tin compound bearing a sulphonic acid, sulfonic acid amide, or sulfonic acid ester group, and a basic nitrogen compound. Storage stable compositions capable of vulcanizing to clear or translucent moldings are produced.