Polyorganosiloxane foams are obtained by blending, dispensing and curing two-part polyorganosiloxane compositions comprising a liquid hydroxyl endblocked polydimethylsiloxane, a liquid alkyl orthosilicate as the curing agent, a catalytically effective amount of a tin compound, a blowing agent and, as a foam stablilizer, a resinous organosiloxane copolymer comprising trimethylsiloxy units, SiO.sub.4/2 units and a specified class of fluorine-containing organosiloxane units.