This study offers a novel and quick enrichment technology that can be used as a preliminary method to obtain a hydrogen-producing species from the biological sludge produced by wastewater treatment. The influences of acid-base enrichment (by sludge PH adjustment) on the anaerobic hydrogen-producing microorganisms were investigated using serum bottle assays. The enrichment PH values were controlled at 3, 4, 5, 7, 10, 11 and 12 with 1 N hydrochloric acid and 1 N sodium hydroxide. For each enrichment PH, the cultivation PH values were controlled at 5, 6 and 7. Based on the experimental results, hydrogen accumulation from sludge with acid or base enrichment is higher than that of the control. The hydrogen-production potential of the sludge with acid or base enrichment is 200 and 333 times enhanced, compared with the control, when the enrichment PH is 10 and 3, respectively. The enhancement is due to a shortening of the micro-organisms' lag-time which occurs at a proper cultivation-PH level.