This paper proposes an un-normalized interval type-2 fuzzy neural network (UIT2FNN) and its application on chaos synchronization. The UIT2FNN combines the advantages of un-normalized interval type-2 fuzzy logic system and neural network. For chaos synchronization, the UIT2FNN plays the role of controller that generates the proper control input such that the two chaotic systems can be synchronized. The simulation and comparison results of Duffing-Holmes system synchronization are presented to illustrate the performance of the proposed UIT2FNN.