Abstract. As a system-level modelling language, SystemC possesses several novel features such as delayed notifications, notification cancelling, notification overriding and delta-cycle. It is challenging to formalise SystemC. In this paper, we study the denotational semantics for SystemC using Unifying Theories of Programming (abbreviated as UTP) [HH98]. Two trace variables are introduced, one to record the state behaviours and another to record the event behaviours. The timed model is formalised in a three-dimensional structure. A set of algebraic laws is explored, which can be proved via the presented denotational semantics.In this paper, we also consider the inverse work; i.e., generating the denotational semantics from algebraic semantics for SystemC. A complete set of parallel expansion laws is explored, where the location status of an instantaneous action is studied. We introduce the concept of head normal form for each program and every program is expressed in the form of guarded choice with location status. Based on this, the derivation strategy for deriving denotational semantics from algebraic semantics is provided.