This paper analyzes the iteration-complexity of a generalized alternating direction method of multipliers (G-ADMM) for solving linearly constrained convex problems. This ADMM variant, which was first proposed by Bertsekas and Eckstein, introduces a relaxation parameter α ∈ (0, 2) into the second ADMM subproblem. Our approach is to show that the G-ADMM is an instance of a hybrid proximal extragradient framework with some special properties, and, as a by product, we obtain ergodic iteration-complexity for the G-ADMM with α ∈ (0, 2], improving and complementing related results in the literature. Additionally, we also present pointwise iteration-complexity for the G-ADMM.2000 Mathematics Subject Classification: 47H05, 49M27, 90C25, 90C60, 65K10.