Structural-chemical transformations of quasi-two-dimensional iron-oxygen nanostructures occurring at transport reduction were studied using NGR spectroscopy. It has been found that isolated iron-oxygen groups [i.e. groups containing iron and oxygen atoms: ≡Si-O-Fe(OH)₂ and (≡Si-O-)₂-FeOH] forming surface monolayers were not reduced at T = 400-600°C because of their covalent bonding with the silica surface. Reduction of iron oxide microparticles (microstructures) at T ≥ 600°C resulted in the formation of metal iron in the form of α-Fe. It has been revealed that in the course of transport reduction (TR) of the samples with deposited monolayers (one or four monolayers) at T ≥ 600°C bulk phases of iron silicate and metal iron were formed. It has also been shown that the features of structural-chemical transformations of supported iron-oxygen nanolayers were in relation with the specific character of phase formation within nanoscale structures.