Weaning is a crucial phase in piglet rearing as the change from milk to solid feed in combination with external stressors such as regrouping may be related to an impaired gut and animal health. Villous atrophy and a limited activity of digestive enzymes can lead to an accumulation of undigested feed in the lower intestinal segments followed by increases in the count of pathogenic bacteria such as E. coli and subsequent diarrhea. Prebiotics are non-digestible feed components that selectively stimulate the growth of positive bacteria such as lactobacilli and may thus reduce pathogens. The present study investigated the potential of a specific prebiotic acid and salt mixture including formic and lactic acid and their salts as well as butyrate and gluconate (PreAcid, Dr. Eckel GmbH, Niederzissen, Germany) in increasing piglet growth and performance. Twenty weaned crossbred piglets each [Pietrain x (Large White x German Landrace)] with an initial bodyweight of 8 ± 1 kg were randomly allocated to a control group and a treatment group. The animals were individually fed a diet based on wheat, barley and soybean meal for a period of 6 weeks and the treatment group received the basal diet supplemented with 1% PreAcid. Statistical analyses were performed using SAS (fixed factors: mother, sex, treatment, group). Energy efficiency (6,139 kcal/kg weight gain vs 6,330 kcal/kg weight gain, P < 0.05) and energy conversion (39 g/kcal vs 38 g/kcal, P < 0.05) were significantly improved by the treatment. In conclusion, the present trial demonstrated that the inclusion of the specific prebiotic acidifier in diets for weaned piglets increased feed efficiency indicating an improved energy utilization.