The type of isomerism shown by the complex $[{\text{CoCl}}_2(\text{en}{)}_2]$ is:

$[{\text{CoCl}}_2(\text{en}{)}_2]$ is an octahedral complex of type $[M{A}_2{B}_2]$ where $B$ is a bidentate ligand. It exists in two forms:Cis-isomer: Where the two $Cl$ ligands are adjacent. It is optically active.Trans-isomer: Where the two $Cl$ ligands are opposite ($180^{\circ }$). It is optically inactive.Since it has cis and trans forms, it shows geometrical isomerism.