At its 9th Session held in Jakarta, Indonesia in November 2012, the Intergovernmental Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System (ICG/IOTWS) decided to organise an Indian Ocean Wave Exercise (IOWave14) in the second half of 2014 and established a Task Team to plan and conduct the exercise. At its recent intersessional meeting held in Hyderabad, India on 27 June, the Task Team decided to conduct the IOWave14 exercise on 9 and 10 September 2014. This letter provides details of the IOWave14 exercise in which all IOTWS Member States are encouraged to participate to the extent possible. IOWave14 will simulate Indian Ocean countries being put in a Tsunami Warning situation and require the National Tsunami Warning Centre (NTWC) and (optionally) the Disaster Management Organisation (DMO) in each Member State to implement their Standard Operating Procedures (SOP). The exercise will comprise two scenarios on successive days, one in the eastern Indian Ocean and the other in the north-western Indian Ocean. The first scenario simulates a magnitude 9.1 earthquake south of Java, Indonesia and the second scenario simulates a magnitude 9.0 earthquake in the Makran Trench south of Iran and Pakistan. Both scenarios will generate simulated tsunami waves travelling across the whole Indian Ocean basin. The South of Java scenario will commence at 0000 hours UTC on 9 September and the Makran Trench scenario will commence at 0600 hours UTC on 10 September. Member States are invited to participate in either or both events, which will run in real time. Regional Tsunami Service Providers in India, Indonesia and Australia will make exercise bulletins and detailed tsunami threat advice available on their password-protected websites during the events, and will send Notification Messages to National Tsunami Warning Centres as the data is updated during the events. An IOWave14 Exercise Manual will be distributed in the near future with further details of the exercise scenarios and the exercise evaluation to be conducted afterwards.