In the present study inocula to combat high acetate (CH3COO-) concentrations during start-up of an anaerobic digestion were designed and evaluated. Two strategies were followed (i) a stepwise adaptation of the engaged microorganisms within 1, 2, 4 or 6 weeks, each at increasing CH3COO- concentrations of 50, 100, and finally 150 mM, and (ii) shock variants, meaning a direct start with 150 mM for the same durations. The stepwise adaptation for 4 and 6 weeks resulted in inocula, leading to a significant improved start-up under high CH3COO- concentrations compared to controls and shock enriched inocula. These results point to the possibility to facilitate the start-up under high CH3COO- concentrations during anaerobic digestion by addition of specific adapted inocula. (C) 2012 Elsevier Ltd. All rights reserved.