Abstract: The present invention provides an organosiloxane comprising at least 80 weight percent of Formula 1: [Y0.01-1.0SiO1.5-2]a{Z0.01-1.0SiO1.5-2]b[H0.01-1.0SiO1.5-2]c (where Y is aryl; Z is alkenyl; a is from 15 percent to 70 percent of Formula 1; b is from 2 percent to 50 percent of Formula 1; and c is from 20 percent to 80 percent of Formula 1. The present organosiloxane may be used as ceramic binder, high temperature encapsulant, and fiber matrix binder. The present composition is also useful as an adhesion promoter in that it exhibits good adhesive properties when coupled with other materials in non-microelectronic or microelectronic applications. Preferably, the present compositions are used in microelectronic applications as etch stops, hardmasks, and dielectrics.