Abstract: Noncrystallizable single-component organopolysiloxane compositions which are storage-stable in the absence of water, curable into elastomers at ambient temperatures and above in the presence of water, and which are well adopted for the production of silicone coatings and seals, include:(A) at least one .alpha.,.omega.-dihydroxydiorganopolysiloxane polymer;(B) a methyltriacetoxysilane cross-linking agent therefor; and(C) an effective amount of at least one additive for preventing the crystallization of said cross-linking agent (B), miscible therewith in all proportions and liquid at ambient temperature, said additive comprising:(i) a diester of ortho-phthalic acid with a monoalcohol of the formula GOH, wherein G is a hydrocarbon radical containing from 4 to 12 carbon atoms; or(ii) an ester of acetic acid with a monoalcohol of the formula G'OH, wherein G' is hydrocabon radical containing from 6 to 18 carbon atoms.