The division of gas/liquid flow at a large diameter T-junction has been studied experimentally. The misdistribution of the phases has been quantified for horizontal semi-annular flow. Film thickness variations about the circumference of the inlet and outlet pipes have been obtained using conductivity techniques. In addition, liquid depth profiles within the junction have been measured. The data have been compared with available theoretical models. (C) 2003 Elsevier Science Ltd. All rights reserved.