IR spectroscopy is coupled with the matrix isolation technique to study the reaction of trimethylsilylketene with HCl. From 50 K trimethylsilylketene reacts with hydrogen chloride, leading to the cleavage of the Si-C bond and the formation of trimethylsilyl chloride and acetyl chloride, through intermediate trimethylsilylacetyl chloride which was identified. A reaction profile for this result is proposed based on a theoretical study carried out at the DFT level.