The local bubble-induced pressure fluctuation signals, which were extracted by Zhang's method [15], were used to identify the flow regime in an inner-loop airlift reactor. For this purpose, local energy ratio and chaotic analysis were employed to extract useful information in detecting the flow regime transition. It was found that local energy ratio was able to indicate the two transition points in the downcomer and two transition points in the riser. Correlation dimension and Kolmogorov entropy can also detect two transition points in the downcomer, but only one transition points in the riser. Since the local energy ratio was easy to calculate, it had a great potential for detecting flow regime transition in an internal-loop airlift reactor or other multiphase systems. (C) 2010 Elsevier B.V. All rights reserved.