A process for dewaxing waxy hydrocarbonaceous materials, such as hydrocarbon fuel and lubricating oil fractions to reduce their cloud and pour points comprises reacting the material with hydrogen in the presence of a dewaxing catalyst comprising at least one metal catalytic component and ferrierite in which at least a portion of its cation exchange positions are occupied by one or more trivalent rare earth metal cations. The rare earth ion exchanged ferrierite catalyst has good selectivity for lubricating oil production, particularly when dewaxing a Fischer-Tropsch wax hydroisomerate. Preferably at least 10% and more preferably at least 15% of the ferreirite cation exchange capacity is occupied by one or more trivalent rare earth metal cations.