 It was found that in the gas phase, dichlorosilane will react with water vapor to give a gaseous monomeric prosiloxane, H2SiO.Prosiloxane polymerizes rapidly in the liquid phase and slowly in the gas phase, which results in liquid and solid polysiloxanes [H2SiO]n. The liquid portion of the product, which is collected via vacuum distillation, becomes viscous and gelled at room temperature.Hydrolysis was done on a solution of H2SiCl2 in benzene by brief contact with water, and the molecular weight was determined to be consistent with an average composition of [H2SiO]6.