In this paper, aiming at output tracking, a decentralized adaptive backstepping control scheme is proposed for a class of interconnected nonlinear time-varying systems. By introducing a bound estimation approach and two smooth functions, the obstacle caused by unknown time-varying parameters and unknown interactions is circumvented and all signals of the overall closed-loop system are proved to be globally uniformly bounded, without any restriction on the parameters variation speed. Moreover, it is shown that the tracking errors can converge to predefined arbitrarily small residual sets with prescribed convergence rate and maximum overshoot, independent of the parameters variation speed and the strength of interactions. Simulation results performed on double inverted pendulums are presented to illustrate the effectiveness of the proposed scheme. (C) 2015 Elsevier Ltd. All rights reserved.