A catalyst for removing nitrogen oxides whose activity deterioration due to volatile poisons contained in exhaust gases is prevented and which has a superior endurance, and a process for producing the catalyst are provided, which catalyst comprises a titania having a surface area of 20 m.sup.2 /g or less and a zeolite having 0.01 to 20% by weight of copper supported thereon; having an average pore diameter of 10 .ANG. or less; and having a silica/alumina molar ratio of 10 or more, and which process comprises mixing powder of the zeolite with the titania or its precursor, followed by molding the mixture into a predetermined shape, followed by calcining the resulting material at 800.degree. C. or higher.