An improved process for preparing the antimicrobial compound flumequine is disclosed. The first step of the process comprises reacting 4-fluoroaniline with crotonaldehyde under acidic conditions at a temperature between 50.degree. and 60.degree. C. In the second step, the product of the first step is slowly added to a refluxing solvent which forms a binary azeotrope with water and has a boiling point between 90.degree. and 120.degree. C. to provide a mixture of 6-fluoroquinaldine and 6-fluorotetrahydroquinaldine. This mixture is then treated with base in the presence of weak acid followed by reducing to provide 6-fluorotetrahydroquinaldine. This compound is then treated according to known procedures to form flumequine.