A silanide is a chemical compound containing an anionic silicon(IV) centre, the parent ion being SiH−3. The hydrogen atoms can also be substituted to produce more complex derivative anions such as tris(trimethylsilyl)silanide (hypersilyl), tris(tert-butyl)silanide, tris(pentafluoroethyl)silanide, or triphenylsilanide. The simple silanide ion can also be called trihydridosilanide or silyl hydride.

The simplest trihydridosilanides can be produced from a triphenylsilanide in a reaction with hydrogen or PhSiH₃ at standard conditions. The triphenylsilanide can be made in a reaction of Ph₃SiSiMe₃ with the metal tert-butoxy compound.

Reacting hydrogen with potassium triphenylsilyl K(Me₆TREN)SiPh₃ can yield potassium silanide.

Other method to form silanides are to heat a heavy metal silicide with hydrogen, or react the dissolved metal with silane.

Atomic metals can react directly with silane to yield unstable molecules with HMSiH₃ formulae. These can be condensed into a noble gas matrix. With titanium this also yields molecules with hydrogen bridging between silicon and titanium.

The silanide ion has an effective ionic radius of 2.26 Å. In salts at room temperature the ion's orientation is not stable, and it rotates. But at lower temperatures (under 200K) silanide becomes fixed in orientation. The ordered structure forms the β- phase, whereas the higher temperature and more symmetrical disordered structure is called α- phase. The β- phase is about 15% more compact than the α-phase.

The silanide ion has C_3v symmetry. The silicon to hydrogen bond length is 1.52 Å and the H-Si-H bond angle is 92.2°, not far off a right angle. In a range of compounds, the stretching force constant for the Si-H bond is 1.9 to 2.05 N cm^–1, which is much softer than that of silane's 2.77 N cm^–1.

Silanide salts are very easily damaged by air or water.