The In 2−xCu xO 3 (x = 0, 0.03, 0.05, and 0.07) thin films were deposited on a glass substrate under vacuum by electron beam evaporation technique. The influence of Cu concentration on the structural, chemical, and magnetic properties of In 2−xCu xO 3 was studied. The Cu concentration did not influence the host crystal structure; however, it does increase the oxygen vacancies and ferromagnetic strength in the In 2−xCu xO 3 system with Cu concentration. X-ray photoelectron spectroscopy revealed the dopant Cu has a Cu(II) state in the In 2O 3 host. The observed ferromagnetism in In 2−xCu xO 3 is similar to the higher oxidation semiconductors (Sn 1−xCu xO 2 and Ti 1−xCu xO 2) and is contrary to the lower oxidation semiconductor (Zn 1−xCu xO). Such a ferromagnetism is attributed to the intrinsic nature of the sample rather than any secondary magnetic phases existing in the films. The observed ferromagnetism in In 2−xCu xO 3 was attributed to the ferromagnetic exchange interaction between Cu 2+ ions via single free electron trapped oxygen vacancy. Increase in oxygen vacancies with Cu concentration leads to increase in such oxygen vacancy-mediated ferromagnetic pairs, resulting in increase in ferromagnetic strength with Cu concentration. However, if we increase Cu concentration above a critical level, Cu–O–Cu interaction leads to an antiferromagnetic nature. © 2015, Springer Science+Business Media New York.