This paper presents an environment which enables the coupling of different supercomputers to overcome the limitations of a single
computing system. This requires an extension to MPI, since MPI provides no interoperability-features. A library called PACX-MPI is
presented which provides the user with a distributed MPI environment with most of the important functionality of standard MPI. First
results were achieved coupling the Cray T3E at the Pittsburgh Supercomputing Center and a Cray T3E at the High Performance
Computing Center in Stuttgart. More recently the coupling of two Cray T3E at the High Performance Computing Center in Juelich and
one Cray T3E of Stuttgart succeded. The first application we have run on the coupled T3E's is the flow simulation package URANUS. Problems and strategies with respect
to metacomputing are discussed briefly for this code. Another application using this library isa Molecular Dynamics Code called
P3T-DSMC. This program was developed for general particle tracking problems. We will present in this paper results for both
applications.