A precursor solution for processing lithium niobate (LiNbO3) films was prepared from lithium niobium ethoxides through modification with acetic acid in hydrolysis. Homogeneous gel films were spin-coated on various substrates. Highly oriented LiNbO3 films were crystallized on sapphire and Pt-coated substrates by heat treatment at 500 °C. Crystallization behavior of the LiNbO3 films depended on the orientation of platinum under-layer films. LiNbO3 films crystallized with preferred (001) orientation on Pt(111) layers, while LiNbO3 films crystallized with preferred (113) orientation on Pt(100) layers. LiNbO3 films prepared on Si(111), SiO2, and MgO(100) substrates showed polycrystalline characteristics with less orientation by heat treatment at 500 °C.