A Banach space X is called a Banach lattice if it is a vector lattice and the norm satisfies the property that if | x |≤| y | implies ∥ x ∥≤∥ y ∥ for every x, y ∈ X. An operator T : X → X is called demicompact if, for every bounded sequence (xn) in X such that (xn − Txn) converges in X , then there is a convergent subsequence of (xn). In this talk, our aim is to use the theory of Banach lattices to provide an approach to the unbounded order weakly demicompact operators. We char- acterize Banach lattices on which all operators are unbounded order weakly demicompact.