Lacking the ability to form hydrogen bonds, acyl chlorides have lower boiling and melting points than similar carboxylic acids. For example, acetic acid boils at 118 °C, whereas acetyl chloride boils at 51 °C. Like most carbonyl compounds, infrared spectroscopy reveals a band near 1750 cm.
The simplest stable acyl chloride is acetyl chloride; formyl chloride is not stable at room temperature, although it can be prepared at –60 °C or below. 
Acyl chlorides hydrolyze (react with water) to form the corresponding carboxylic acid and hydrochloric acid: