Domain-specific modelling languages provide modelling means tailored to a particular domain. In Model-driven Engineering, it is common practice to specify such languages by modelling means as well. In this paper, we investigate structural operational semantics for domainspecific modelling languages. Thereby, we rely completely on standard modelling means as provided by the Object Management Group. As examples, we specify structural operational semantics for Petri nets as well as for a stream-oriented language from the domain of earthquake detection. The approach is useful to provide prototypical tool support for domain-specific modelling languages. It can be instrumented to specify interpreters and debuggers in a generic way.