Various samples of beta-NiMoO4 phase consisting of nickel and molybdenum in a stoichiometric ratio were prepared by precipitation from nickel nitrate hexahydrate and ammonium heptamolybdate, and also in presence of Si(OCH3)(4) and Si(OEt)(3)(CH2)(3)NH(CH2)NH2 using the sol-gel method. The stabilised beta-NiMoO4 phase is synthesised using the sol-gel technique. The development of this phase is achieved by using a direct crystallisation in the silica matrix due to a high dispersion of Ni and Mo salts into silica gels derived from silicon alkoxides hydrolysis and condensation reactions. The mutual influences in hydroalcoholic solutions between the two growing phases, i.e. the molybdate crystallites ions and the silica colloidal oligomers particles, cause a dramatic increase in the gelation rate. The gel thermal treatment causes the ionic species migration to form highly dispersed nanometer-sized NiMoO4 crystallites of ca. 120 nm. XRD, Raman, TG-DTG, and XPS techniques were used for the characterisation of the material. The solids are semicrystalline materials with a surface area of 280 m(2) g(-1). DTG and XPS analyses provide evidence for the interactions between SiO2 and NiMoO4 systems which are responsible for the stabilisation of beta-NiMoO4. Unsupported beta-NiMoO4 is a high-temperature metastable phase; it transforms (back transition) into alpha-NiMoO4 at ca. 250 T, while beta-NiMoO4 stabilised by a silica matrix does not. (C) 2003 Published by Elsevier Ltd.