Single-step fabrication of thin films of Ge/GeO2 and NdAlO3/Al2O3 nanocomposites is achieved by the chemical vapour deposition of single molecular compounds [Ge(OBui)(2)](2) and [NdAl3(OPri)(12)((PrOH)-O-i)], respectively. The Ge/GeO2 film is constituted by the distribution of Ge crystals in a GeO2 matrix. Since the biphasic composite is formed by the disproportionation of a single metastable species, a self-organization of the two phases is observed. The structural elucidation by X-ray photoelectron spectroscopy and nanoindentation studies confirmed a core-shell type constitution of the composite particles. The oxide-oxide composite is formed by a homogeneous dispersion of NdAlO3 nanocrystals in an amorphous Al2O3 matrix. Al-27 solid-state NMR and XPS studies established the diphasicity of the system. HR-TEM analysis revealed a composite structure formed by NdAlO3 nanocrystals evenly distributed in a matrix of alumina particles. NdAlO3/Al2O3 composite exhibits a higher absorption and photo luminescence efficiency than monophasic NdAlO3, which is attributed to the isolation of NdAlO3 crystals by the alumina matrix, and a cooperative energy transfer of the absorbed pump energy from Al3+ to Nd3+ ions.