Abstract. The Chemical Formulation Problem (Compounding Problem) consists in modifying the chemical formulation of a compound in order to obtain a new compound showing a set of desired performances. This paper presents a computational model for the Compounding Problem based on the interpretation of transformation actions on the compound structures as ABox updates. Possible transformations of the compounds are defined as transitions of a Labelled Transition System (LTS), and the Compounding Problem has been defined as a Heuristic Search Problem. In order to reduce the complexity of the search space the paper presents an approach based on: (i) the representation of the ontological constraints on the compounds’ structure in a TBox, and the representation of compound formulations as ABoxes. (ii) The representation of the transitions of a LTS as a set of actions producing updates on ABoxes; (iii) the definition of an algorithm to check ABox consistency with respect to a specific axiom...