Abstract: A process for the preparation of aromatic aldehydes containing fluorine, and more particularly, to a formylation process for fluorinated aromatic derivatives through the reaction of fluorinated benzenes with carbon monoxide and aluminum chloride at a relatively low pressure, a low temperature, and in the presence of at most a catalytic amount of an acid (such as aqueous hydrochloric acid) is herein disclosed. The resultant fluorinated benzaldehydes are useful as precursors to the formation of a number of different compounds, such as dyestuffs, flavorings, fragrances, herbicidal compounds, nucleating agents, polymer additives, and the like. The inventive method provides a very cost effective and safe procedure for producing such fluorinated benzaldehydes in very high yields.