Current thermal-hydraulic analysis codes use static, flow-regime-dependent empirical models which introduce several sources of error and numerical instability. The interfacial area transport equation offers a more robust, reliable prediction of interfacial area and can allow for dynamic predictions of two-phase flows. In order to develop reliable mechanistic models for interfacial area concentration sources and sinks an extensive database is required, however the current database lacks significant data for pipes larger than 0.1. m diameter and for void fractions above 0.4. To improve and extend the database experiments have been performed in pipes with diameters of 0.152. m and 0.203. m with void fractions of up to 0.7, providing valuable data regarding the local profiles and axial development that can be used to evaluate current interfacial area transport models and assist in the development of new mechanistic models for interfacial area concentration sources and sinks. © 2012 Elsevier Inc.