First-principles density functional theory is employed to study the electrical behavior of oxygen and indium vacancies in indium oxide (In(2)O(3)). The oxygen vacancy is found to be a double donor. The indium vacancy is a triple acceptor, which >can be a compensation center in n-type In(2)O(3), leading to n-type carrier reduction. However, its high formation energy under p-type conditions makes it unlikely to be a source of p-type carriers by itself. (C) 2011 Elsevier B.V. All rights reserved.