A new reductive dimerization and oligomerization reaction of (C-5 and C-6) cycloalkanols and cycloalkanones, benzaldehyde, and benzyl alcohol to hydrocarbons containing as many, or more, carbon atoms as the reactant oxygenated compound on a promoted, fused iron catalyst proceeds at a temperature of 250-350A degrees C, a hydrogen pressure of 0.1-1 MPa, a specific feed rate of oxygenated reagent of 80-320 g h(-1)kg(-1)Ct, and a hydrogen space velocity of 1 x 10(3) to 20 x 10(3) h(-1). Possible reaction mechanisms have been considered.