Summary: The paper aims at defining hierarchical time extensions of M-nets, a fully compositional class of high-level Petri nets. As a starting point, the class of classical timed M-nets are considered, where time intervals of duration are attached to each transition. This class is enriched by two new operations: timed refinement (which extends the class) and hierarchical scoping (which is shown to be a powerful feature for abstraction). It is argued that hierarchical timed M-nets permit the design of real-time systems in a top down manner. Moreover, a partial order semantics of hierarchical timed M-nets is defined based on branching processes. The definition is given directly for high level nets, without preliminary unfolding to low level nets. This semantics enables partial order model checking of hierarchical timed M-nets e.g. within the PEP-system.