The investigation presented here is in two parts: a mechanistic study of the triethylamine dehydrohalogenation of ac-haloacid halides to form halogenated ketenes and a study of steric influence upon ketene lifetimes. The first part of this research deals with the mechanism of the dehydrohalogenation reaction. Two acid halides, isobutyryl chloride and a-chloropropionyl chloride, appeared to represent two mechanistic extremes for this reaction with triethylamine. Isobutyryl chloride reacted with triethylamine to form an acylammonium salt while a-chloropropionyl chloride produced the enolate salt. These salts were detected in chloroform solution by both nuclear magnetic resonance spectra and infrared spectra. The results of the investigation into the mechanism of dehydrohalogenation and ketene lifetime were complemented by CNDO/2 calculations of the acid halides and ketenes studied. It was concluded that the mechanism of dehydrohalogenation of acid halides involves a complex series of equilibria,and it has become increasingly apparent that halogenated ketenes are produced through the acylammonium salt. The enolate salt appears to be a dead end in the reaction to form ketenes. It was also demonstrated that increasing steric bulk has a stabilizing effect on ketene lifetimes.