The possibility of spin-coating crystalline multi-element oxide model catalysts using citrate complexes of Bi3+ and Mo6+ solutions was studied. The characterization of obtained thin films was performed by XRD, Raman spectroscopy, SEM and XPS. XRD and confocal Raman data indicated that Bi2O3-MoO3 mixed systems behaved as dictated by the composition of the starting solutions, and pure alpha-Bi2Mo3O12, beta-Bi2Mo2O9, and gamma-Bi2MoO6 phases were obtained without any heterogeneity. XPS confirmed that Bi:Mo ratios at the surface of the films never differed from those in the bulk, namely that of the starting co-solutions. SEM revealed that the thickness of the films could be tuned in the range 40-140 mn via adjustment of the spinrate (2, 3, or 5 krpm) and the concentration of the precursors solution (0.24 or 0.48 M in Mo), without any disturbance of crystallinity, the Bi:Mo ratio or the homogeneity of the films. Performed studies suggested that spin-coating of mixed citrate complexes appears as a versatile and easy route to prepare homogenous films of multi-element transition metal oxides with controlled formulation and crystalline structure. (c) 2007 Elsevier B.V All rights reserved.