The Democratic Republic of Timor-Leste (East Timor) attained independence on 20 May 2002, marking its separation from Indonesia. As a newly independent country, East Timor is faced with a number of significant international opportunities, together with some obligations that it must fulfil, including the delimitation of its international boundaries. Similarly, for Indonesia, with 10 maritime neighbours, the delimitation of maritime boundaries is a significant challenge. This paper describes a preliminary study on the delimitation of the Indonesia - East Timor maritime boundary, with a focus on technical aspects. Geospatial data has been obtained from the Indonesian government and processed with the assistance of a specialised Geographic Information Systems (GIS) application: CARIS LOTSTM. The main tasks are to simulate the maritime claims of Indonesia and East Timor, to identify overlapping claims and to delimit theoretical maritime boundaries between the two states. The United Nations Convention on the Law of the Sea 1982, LOSC, provides the main legal reference point, along with relevant state practice and jurisprudence. Potential delimitation lines were calculated in a geodetically robust manner. Three major locations for maritime boundaries were identified as requiring delimitation. These are in the Ombai Strait, the Wetar Strait and in the Timor Sea. A number of alternative potential boundary alignments have also been examined and analysed for the three locations, in the context of future maritime boundary negotiations between the two States. However, the results presented are not the final boundaries that Indonesia and East Timor are bound to accept. Ultimately it is for the governments of Indonesia and East Timor to negotiate an equitable solution that will satisfy both parties. However, it is hoped that this study will contribute towards achieving that goal.