The current study investigated the combined effects of N-acetylcysteine and working memory (WM) training on behavioral and neural mechanisms of cue reactivity and WM in cocaine users in a randomized, double-blind design. Twenty-four of 38 cocaine-using men completed a 25-day treatment with either 2400 mg/day NAC or placebo. Both groups performed WM-training. During pre- and post-test lab-visits, neural mechanisms of cue reactivity and WM, and cue-induced craving and WM performance were assessed. Additionally, exploratory whole brain analyses were performed. Overall, the hypotheses were not confirmed, possibly due to small sample size, low WM-training adherence and/or ongoing substance use.