The influences of pH and dissolved CO2 level on the regulation of growth and formation of catabolic end products have been investigated in Klebsiella pneumoniae. With increasing CO2 levels, there were no apparent changes in 2,3-butanediol production but succinic acid productions were enhanced significantly. A novel strategy for co-production of 2,3-butanediol and succinic acid using K. pneumoniae was developed by controlling pH and dissolved CO2 concentration in fermentation medium. Under the optimum condition, maximal 77.1 gl(-1) 2,3-butanediol and 28.7 gl(-1) succinic acid were obtained after 60 h of fed-batch fermentation, giving a 2,3-butanediol + succinic acid yield of 1.03 mol mol(-1) glucose. This type of fermentation producing two commercial interests at the same fermentation process might be considered for a promising biological production process which will decrease the production cost by sharing the operation and recovery cost.(C) 2012 Elsevier Ltd. All rights reserved.