Polycrystalline alpha-AgGaO2 powders were prepared by the hydrothermal conversion of beta-AgGaO2. The beta-AgGaO2 was synthesized by the ion exchange reaction between NaGaO2 and molten AgNO3 under nitrogen atmosphere. The alpha-AgGaO2 thus synthesized was used as the target for pulsed laser ablation. The films grown on alpha-Al2O3 (0001) single crystal substrates are crystalline and are 50% transparent in the visible region. The temperature dependence of conductivity shows a semiconducting behaviour with room temperature conductivity 3 x 10(-4) Scm(-1). The positive sign of Seebeck coefficient (+70 mu VK-1) demonstrated the p-type conduction in the films. Transparent p-n heterojunctions on a glass substrate were fabricated. The structure of the device was glass/ITO/n-ZnO/p-AgGaO2. The ratio of forward to reverse current was more than 100 in the range of -1.5 V to + 1.5 V. (c) 2007 Elsevier B.V. All rights reserved.