The purpose of this work is to present a simplified demonstration of Co- ecke's Compositionality Theorem, which refers to the quantum information processing associated to n-partite entangled states. By using the universal property of the tensor product in our proof, we will see that is possible to consider all the relevant states as being product states, which turns the demonstration much easier. We will present also the teleportation process of quantum states, so called nowadays, and verify finally that such a process is a trivial application of Coecke's theorem