The thermal decomposition of chloroacetyl chloride, propanoyl chloride, 3-chloropropanoyl chloride, acryloyl chloride, E-2-butenoyl chloride, methacryloyl chloride, and cyclopropanecarbonyl chloride has been investigated using infrared laser-powered homogeneous pyrolysis, together with product analysis using IR spectroscopy, gas chromatography/mass spectrometry, matrix isolation spectroscopy and tuneable diode laser spectroscopy. Decomposition is usually initiated by 1,2-HCl elimination (where possible), followed by further decomposition of ketene products. Reaction pathways have been validated in many cases by the ab initio calculation of activation energies.