In geometry of 4 dimensions, a **10-10 duoprism** is a polygonal duoprism, a 4-polytope resulting from the Cartesian product of two decagons.

It has 100 vertices, 200 edges, 120 faces (100 squares, and 20 decagons), in 20 decagonal prism cells. It has Coxeter diagram , and symmetry [[10,2,10]], order 800.

The uniform *10-10 duoprism* can be constructed from [10]×[10] or [5]×[5] symmetry, order 400 or 100, with extended symmetry doubling these with a 2-fold rotation that maps the two orientations of prisms together.

The regular complex polytope _{10}{4}_{2}, , in
C
2
has a real representation as a 10-10 duoprism in 4-dimensional space. _{10}{4}_{2} has 100 vertices, and 20 10-edges. Its symmetry is _{10}[4]_{2}, order 200.

It also has a lower symmetry construction, , or _{10}{}×_{10}{}, with symmetry _{10}[2]_{10}, order 100. This is the symmetry if the red and blue 10-edges are considered distinct.

The dual of a *10-10 duoprism* is called a **10-10 duopyramid**. It has 100 tetragonal disphenoid cells, 200 triangular faces, 120 edges, and 20 vertices.

Orthogonal projection

The regular complex polygon _{2}{4}_{10} has 20 vertices in
C
2
with a real representation in
R
4
matching the same vertex arrangement of the 10-10 duopyramid. It has 100 2-edges corresponding to the connecting edges of the 10-10 duopyramid, while the 20 edges connecting the two decagons are not included.

The vertices and edges makes a complete bipartite graph with each vertex from one decagon is connected to every vertex on the other.