In chemistry, the capped square antiprismatic molecular geometry describes the shape of compounds where nine atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a gyroelongated square pyramid.

It is very similar to the tricapped trigonal prismatic molecular geometry, and there is some dispute over the specific geometry exhibited by certain molecules.

Examples: Square antiprisms can be capped on both square faces, giving bicapped square antiprismatic molecular geometry.

The bicapped square antiprismatic atoms surrounding a central atom define the vertices of a gyroelongated square bipyramid.

[2] The symmetry group of this object is D4d.