In this work we report a new RCVD technique which allows the deposition of nonvolatile compounds from the gas phase into thin films. The technique developed is based on the metathesis reaction in the gas phase between the volatile reagents with the following deposition of the nonvolatile product. A novel RCVD reactor has been constructed and consists of two evaporation (T 1 , T 2) zones connected to the reaction zone (T 3). This approach has been successfully tested on terbium carboxylates (Tb(Carb) 3 ; HCarb ¼ Hbz (benzoic acid), Hpobz (o-phenoxybenzoic acid)) as nonvolatile but promising complexes for their application as thin film optical materials. We demonstrated that the construction of the reactor plays a crucial role in the controlling of the films composition, morphology and thickness. The optimal parameters have been found and Tb(Carb) 3 thin films with roughness $2–4 nm and thickness in the range of $40–200 nm were obtained.