Abstract: An improved base synthesis process and catalyst for the preparation of pyridine or its alkylpyridine derivatives involving the catalytic reaction of one or more aldehydes and/or ketones containing from one to about five carbon atoms, with at least one reactant having more than one carbon atom, with ammonia in the gas phase. The improved catalyst comprises an effective amount of a shape-selective zeolite which has been modified by treatment with one or more metal ions or compounds of tungsten. zinc or tin. The preferred zeolite has a constraint index of about 1 to 12 and a high silica content and correspondingly low concentration of ion-exchange sites with minimal to no acidic sites present.