Crosslinkable compositions comprise novel organosilicon compounds (B.sup.1) containing Si-bonded hydrogen atoms and comprising(a) units of the formulaH.sub.a R.sub.2-a SiO.sub.2 O.sub.2/2 (I), where R is as defined in claim 1 and a is 0, 1 or 2, with the proviso that at least 20 mol % of the units of the formula (I) are ones in which a is 1 or 2,(b) carbostructural units G (II), where G are identical or different and are each a trivalent to decavalent aliphatic hydrocarbon radical having from 7 to 30 carbon atoms per radical, which may contain one or more heteroatoms selected from the group consisting of oxygen, boron, silicon, tin or titanium, with the proviso that at least three Si atoms are connected to one another via G,(c) units of the formula ##STR1## where b is 0, 1 or 2, with the proviso that b in formula (III') is not 2 and with the proviso that the units of the formula (III) or (III') are connected via the Si atoms to the carbostructural units G and(d) units of the formulaH.sub.c R.sub.3-c SiO.sub.1/2 (I), where c is 0, 1 or 2, with the proviso that the organosilicon compounds (B.sup.1) contain on average at least 6 Si-bonded hydrogen atoms.