The purpose of the present work is to experimentally study the effects of the oxygen gas flow rate and ion beam plasma conditions on the properties of indium molybdenum oxide (IMO) films deposited onto the polyethersulfone (PES) substrate. Crystal structure, surface morphology, and optoelectronic properties of IMO films are examined as a function of oxygen gas flow rate and ion beam discharge voltage. Experimental results show that the IMO films consist of a cubic bixbyite B-In2O3 single phase with its crystal preferred orientation alone B(222). Mo6+ ions are therefore considered to partially substitute In3+ sites in the deposit. Under-controlled ion bombardment during deposition enhances the reaction among those arriving oxygen and metal ion species to condense into IMO film and facilitates a decreased surface roughness of IMO film. The film with ultimate crystallinity and the lowest surface roughness is obtained when the oxygen flow rate of 3 sccm and the discharge voltage of 110 Vare employed. This results in the lowest electrical resistivity due mainly to the increased Hall mobility and irrelevant to carrier concentration. The lowest electrical resistivity of 8.63 x 10(-4) ohm-cm with a 84.63% transmittance at a wavelength of 550 nm can be obtained, which satisfies the requirement of a flexible transparent conductive polymer substrate. (c) 2007 Elsevier B.V. All rights reserved.