Copper(I) iodide reacts with mercury vapors to form copper tetraiodomercurate:
:4CuI  +  Hg  →  CuHgI  +  2Cu
This reaction can be used for the detection of mercury since the white (CuI) to brown (CuHgI) color change is dramatic.
Copper(I) iodide is used in the synthesis of Cu(I) clusters such as . 
Copper(I) iodide dissolves in acetonitrile, yielding diverse complexes. Upon crystallization, molecular or polymeric compounds can be isolated. Dissolution is also observed when a solution of the appropriate complexing agent in acetone or chloroform is used. For example, thiourea and its derivatives can be used. Solids that crystallize out of those solutions are composed of hybrid inorganic chains.