Abstract: Continuous Petri nets are an approximation of discrete Petri nets introduced to cope with the state explosion problem typical of discrete event systems. In this talk we consider the state estimation problem for this class of models trying to determine all states that are consistent with observed sequence of transition firings. Firstly, we show how the results previously obtained for discrete nets can be applied, with minor modifications, to untimed continuous net systems. Secondly, we consider timed continuous Petri nets with finite server semantics. Under the assumption that no observation is available, and thus the set of consistent markings only depends on the time elapsed, we study the observation based on the time-reachability analysis.